feat(content): scenes + shared-colors + colour-presets endpoints

Completes the content backend for the studio building blocks (all project-scoped):
- GET /v1/scenes?project_id= + POST/PUT/DELETE (scene metadata CRUD)
- GET /v1/shared-colors?project_id= + POST/PUT/DELETE
- GET /v1/color-presets?project_id= + POST/PUT/DELETE (palette + items)
SceneColorService + DTOs; reads open, writes [Authorize(Roles=Admin)].
Gateway routes /v1/{scenes,shared-colors,color-presets}/* → content.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

services/content/FlatRender.ContentSvc/Application/Services/SceneColorService.cs

@@ -0,0 +1,190 @@
+using FlatRender.ContentSvc.Domain.Entities;
+using FlatRender.ContentSvc.Domain.Enums;
+using FlatRender.ContentSvc.Infrastructure.Data;
+using FlatRender.ContentSvc.Models;
+using Microsoft.EntityFrameworkCore;
+
+namespace FlatRender.ContentSvc.Application.Services;
+
+/// <summary>CRUD for project-scoped scenes, shared colors and colour presets.</summary>
+public class SceneColorService(ContentDbContext db)
+{
+    // ── Scenes ──────────────────────────────────────────────────────────────
+
+    public async Task<List<SceneResponse>> GetScenesAsync(Guid projectId) =>
+        await db.Scenes.Where(s => s.ProjectId == projectId && s.DeletedAt == null)
+            .OrderBy(s => s.Sort)
+            .Select(s => ToSceneResponse(s)).ToListAsync();
+
+    public async Task<SceneResponse> CreateSceneAsync(CreateSceneRequest req)
+    {
+        var scene = new Scene
+        {
+            ProjectId = req.ProjectId,
+            Key = req.Key,
+            Title = req.Title,
+            LocalizedTitle = req.LocalizedTitle,
+            SceneType = ParseSceneKind(req.SceneType),
+            Image = req.Image,
+            Demo = req.Demo,
+            SceneColorSvg = req.SceneColorSvg,
+            SnapshotUrl = req.SnapshotUrl,
+            GenerateKf = req.GenerateKf,
+            DefaultDurationSec = req.DefaultDurationSec,
+            MinDurationSec = req.MinDurationSec,
+            MaxDurationSec = req.MaxDurationSec,
+            OverlapAtEndSec = req.OverlapAtEndSec,
+            CanHandleDuration = req.CanHandleDuration,
+            ManualColorSelection = req.ManualColorSelection,
+            Sort = req.Sort,
+            IsActive = req.IsActive,
+        };
+        db.Scenes.Add(scene);
+        await db.SaveChangesAsync();
+        return ToSceneResponse(scene);
+    }
+
+    public async Task<SceneResponse> UpdateSceneAsync(Guid id, UpdateSceneRequest req)
+    {
+        var scene = await db.Scenes.FindAsync(id) ?? throw new KeyNotFoundException($"Scene {id} not found");
+        scene.Key = req.Key;
+        scene.Title = req.Title;
+        scene.LocalizedTitle = req.LocalizedTitle;
+        scene.SceneType = ParseSceneKind(req.SceneType);
+        scene.Image = req.Image;
+        scene.Demo = req.Demo;
+        scene.SceneColorSvg = req.SceneColorSvg;
+        scene.SnapshotUrl = req.SnapshotUrl;
+        scene.GenerateKf = req.GenerateKf;
+        scene.DefaultDurationSec = req.DefaultDurationSec;
+        scene.MinDurationSec = req.MinDurationSec;
+        scene.MaxDurationSec = req.MaxDurationSec;
+        scene.OverlapAtEndSec = req.OverlapAtEndSec;
+        scene.CanHandleDuration = req.CanHandleDuration;
+        scene.ManualColorSelection = req.ManualColorSelection;
+        scene.Sort = req.Sort;
+        scene.IsActive = req.IsActive;
+        scene.UpdatedAt = DateTime.UtcNow;
+        await db.SaveChangesAsync();
+        return ToSceneResponse(scene);
+    }
+
+    public async Task DeleteSceneAsync(Guid id)
+    {
+        var scene = await db.Scenes.FindAsync(id) ?? throw new KeyNotFoundException($"Scene {id} not found");
+        scene.DeletedAt = DateTime.UtcNow;
+        await db.SaveChangesAsync();
+    }
+
+    // ── Shared colours ──────────────────────────────────────────────────────
+
+    public async Task<List<SharedColorResponse>> GetSharedColorsAsync(Guid projectId) =>
+        await db.SharedColors.Where(c => c.ProjectId == projectId).OrderBy(c => c.Sort)
+            .Select(c => new SharedColorResponse(c.Id, c.ProjectId, c.ElementKey, c.Title, c.Icon,
+                c.AttrValue.ToString(), c.DefaultColor, c.Sort)).ToListAsync();
+
+    public async Task<SharedColorResponse> CreateSharedColorAsync(SaveSharedColorRequest req)
+    {
+        var c = new SharedColor
+        {
+            ProjectId = req.ProjectId,
+            ElementKey = req.ElementKey,
+            Title = req.Title,
+            Icon = req.Icon,
+            AttrValue = ParseAttrValue(req.AttrValue),
+            DefaultColor = req.DefaultColor,
+            Sort = req.Sort,
+        };
+        db.SharedColors.Add(c);
+        await db.SaveChangesAsync();
+        return new SharedColorResponse(c.Id, c.ProjectId, c.ElementKey, c.Title, c.Icon, c.AttrValue.ToString(), c.DefaultColor, c.Sort);
+    }
+
+    public async Task<SharedColorResponse> UpdateSharedColorAsync(Guid id, SaveSharedColorRequest req)
+    {
+        var c = await db.SharedColors.FindAsync(id) ?? throw new KeyNotFoundException($"Color {id} not found");
+        c.ElementKey = req.ElementKey;
+        c.Title = req.Title;
+        c.Icon = req.Icon;
+        c.AttrValue = ParseAttrValue(req.AttrValue);
+        c.DefaultColor = req.DefaultColor;
+        c.Sort = req.Sort;
+        c.UpdatedAt = DateTime.UtcNow;
+        await db.SaveChangesAsync();
+        return new SharedColorResponse(c.Id, c.ProjectId, c.ElementKey, c.Title, c.Icon, c.AttrValue.ToString(), c.DefaultColor, c.Sort);
+    }
+
+    public async Task DeleteSharedColorAsync(Guid id)
+    {
+        var c = await db.SharedColors.FindAsync(id) ?? throw new KeyNotFoundException($"Color {id} not found");
+        db.SharedColors.Remove(c);
+        await db.SaveChangesAsync();
+    }
+
+    // ── Colour presets (palettes) ───────────────────────────────────────────
+
+    public async Task<List<ColorPresetResponse>> GetColorPresetsAsync(Guid projectId) =>
+        await db.SharedColorPresets.Where(p => p.ProjectId == projectId).OrderBy(p => p.Sort)
+            .Select(p => new ColorPresetResponse(p.Id, p.ProjectId, p.Name, p.Sort,
+                p.Items.OrderBy(i => i.Sort).Select(i => new ColorPresetItemResponse(i.Id, i.ElementKey, i.Value, i.Sort)).ToList()))
+            .ToListAsync();
+
+    public async Task<ColorPresetResponse> CreateColorPresetAsync(SaveColorPresetRequest req)
+    {
+        var preset = new SharedColorPreset
+        {
+            ProjectId = req.ProjectId,
+            Name = req.Name,
+            Sort = req.Sort,
+            Items = (req.Items ?? []).Select(i => new SharedColorPresetItem
+            {
+                ElementKey = i.ElementKey, Value = i.Value, Sort = i.Sort,
+            }).ToList(),
+        };
+        db.SharedColorPresets.Add(preset);
+        await db.SaveChangesAsync();
+        return await GetPresetAsync(preset.Id);
+    }
+
+    public async Task<ColorPresetResponse> UpdateColorPresetAsync(Guid id, SaveColorPresetRequest req)
+    {
+        var preset = await db.SharedColorPresets.Include(p => p.Items).FirstOrDefaultAsync(p => p.Id == id)
+            ?? throw new KeyNotFoundException($"Preset {id} not found");
+        preset.Name = req.Name;
+        preset.Sort = req.Sort;
+        db.SharedColorPresetItems.RemoveRange(preset.Items);
+        preset.Items = (req.Items ?? []).Select(i => new SharedColorPresetItem
+        {
+            PresetId = preset.Id, ElementKey = i.ElementKey, Value = i.Value, Sort = i.Sort,
+        }).ToList();
+        await db.SaveChangesAsync();
+        return await GetPresetAsync(preset.Id);
+    }
+
+    public async Task DeleteColorPresetAsync(Guid id)
+    {
+        var preset = await db.SharedColorPresets.FindAsync(id) ?? throw new KeyNotFoundException($"Preset {id} not found");
+        db.SharedColorPresets.Remove(preset);
+        await db.SaveChangesAsync();
+    }
+
+    private async Task<ColorPresetResponse> GetPresetAsync(Guid id) =>
+        await db.SharedColorPresets.Where(p => p.Id == id)
+            .Select(p => new ColorPresetResponse(p.Id, p.ProjectId, p.Name, p.Sort,
+                p.Items.OrderBy(i => i.Sort).Select(i => new ColorPresetItemResponse(i.Id, i.ElementKey, i.Value, i.Sort)).ToList()))
+            .FirstAsync();
+
+    // ── helpers ─────────────────────────────────────────────────────────────
+
+    private static SceneResponse ToSceneResponse(Scene s) => new(
+        s.Id, s.ProjectId, s.Key, s.Title, s.LocalizedTitle, s.SceneType.ToString(),
+        s.Image, s.Demo, s.SceneColorSvg, s.SnapshotUrl, s.GenerateKf,
+        s.DefaultDurationSec, s.MinDurationSec, s.MaxDurationSec, s.OverlapAtEndSec,
+        s.CanHandleDuration, s.ManualColorSelection, s.Sort, s.IsActive);
+
+    private static SceneKind ParseSceneKind(string? v) =>
+        Enum.TryParse<SceneKind>(v, true, out var k) ? k : SceneKind.Normal;
+
+    private static AttrValueKind ParseAttrValue(string? v) =>
+        Enum.TryParse<AttrValueKind>(v, true, out var a) ? a : AttrValueKind.fill;
+}