feat: V2 microservices stack — backend services, gateway, JWT auth

Add full V2 architecture: identity, content, studio (.NET 10) and file,
render, notification, gateway (Go) services with vendored deps, plus DB
migrations, event/API contracts, and an init-db script.

Wire the Next.js frontend to the gateway: server-side JWT auth routes
(login/register/refresh/logout/me), gateway fetch helper, and session/
cookie/jwt helpers under src/lib.

Containerize the stack via docker-compose.v2.yml and per-service
Dockerfiles. Base images resolve through a Nexus mirror (Docker Hub) and
MCR directly; npm/NuGet pull from Nexus groups. Self-host fonts via
next/font/local to avoid Google Fonts (geo-blocked).

Add CI workflow and ignore .env.v2, *.stackdump, and .NET bin/obj.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

services/studio/FlatRender.StudioSvc/Models/Requests/Requests.cs

@@ -0,0 +1,125 @@
+namespace FlatRender.StudioSvc.Models.Requests;
+
+public record CreateSavedProjectRequest(
+    Guid OriginalProjectId,
+    string? Name,
+    Guid? PresetStoryId,
+    bool CopyDefaultValues = true
+);
+
+public record UpdateSavedProjectRequest(
+    string? Name,
+    string? Image,
+    string? Type,
+    Guid? MusicFileId,
+    Guid? MusicTrackId,
+    decimal? MusicVolume,
+    Guid? VoiceoverFileId,
+    decimal? VoiceoverVolume,
+    bool? VoiceoverRecordedInBrowser,
+    decimal? SfxVolume,
+    bool? SfxEnabled,
+    string? AudioVisualizerMusicUrl,
+    decimal? AudioVisualizerDurationSec,
+    bool? ManualColorPicker,
+    Guid? SelectedPresetStoryId,
+    string? LastEditStep,
+    string? EditState
+);
+
+public record SaveSceneRequest(
+    Guid? OriginalSceneId,
+    string Key,
+    string? Title,
+    string? Image,
+    string? SceneColorSvg,
+    string SceneType,
+    int Sort,
+    decimal SceneLengthSec,
+    decimal? MinDurationSec,
+    decimal? MaxDurationSec,
+    decimal OverlapAtEndSec,
+    bool CanHandleDuration,
+    bool ManualColorSelection,
+    List<SaveSceneContentRequest> Contents,
+    List<SaveSceneColorRequest> Colors,
+    List<SaveSharedColorRequest> SharedColors,
+    List<SaveSharedLayerRequest> SharedLayers
+);
+
+public record SaveSceneContentRequest(
+    string Key,
+    string? Title,
+    string Type,
+    string? Value,
+    Guid? ValueFileId,
+    string? InsertedFileType,
+    string? FontFace,
+    string? FontFaceName,
+    int? FontSize,
+    int? DefaultFontSize,
+    string? DefaultFontFace,
+    string? Justify,
+    int PositionInContainer,
+    int DirectionLayerValue,
+    bool IsTextBox,
+    string? AiInputType,
+    int? SelectedDp,
+    string? RepeaterItemKey,
+    int? RepeaterIndex,
+    bool IsFocused,
+    string? MappedList,
+    string? Thumbnail,
+    int Sort
+);
+
+public record SaveSceneColorRequest(
+    string ElementKey,
+    string? Title,
+    string? Icon,
+    string AttrValue,
+    string Value,
+    bool IsSelected,
+    int Sort
+);
+
+public record SaveSharedColorRequest(
+    string ElementKey,
+    string? Title,
+    string? Icon,
+    string AttrValue,
+    string Value,
+    bool IsSelected,
+    int Sort
+);
+
+public record SaveSharedLayerRequest(
+    string Key,
+    string? Title,
+    string Type,
+    string? Value,
+    Guid? ValueFileId,
+    string? FontFace,
+    string? FontFaceName,
+    int? FontSize,
+    string? Justify,
+    int PositionInContainer,
+    int DirectionLayerValue,
+    bool IsTextBox,
+    string? AiInputType,
+    string? MappedList,
+    string? Thumbnail,
+    int? Width,
+    int? Height,
+    bool IsFocused,
+    bool IsFontChangeable,
+    bool IsFontSizeChangeable,
+    int Sort
+);
+
+public record SavedProjectListRequest(
+    int Page = 1,
+    int PageSize = 20,
+    string? Q = null,
+    string? Type = null
+);