fix(seed): real per-scene images for every scene (were only colour swatches)

Scenes were seeded with just a scene_color_svg swatch — content.scenes.image /
snapshot_url were empty, so the studio/admin scene previews showed swatches, not
the actual scene. Now every scene gets a real rendered image:
- single-scene templates → their per-aspect thumbnail;
- multi-scene templates → one still per scene, captured at that scene's own frame.

Adds the 39 CharacterStory per-scene stills (13 scenes × 3 aspects), each rendered
at (sceneIndex*90 + 45). LogoMotion3D's single scene now points at its thumbnail.
Verified: DB image/snapshot_url populated, all per-scene images serve 200, and the
stills are distinct per scene (c7 = «یک مانع», kicker ۰۷/۱۳).

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

scripts/seed_remotion_templates.py

@@ -143,17 +143,18 @@ for idx, (tid, slug, name, desc, dur, texts, (accent, sec, bg)) in enumerate(T):
             # one editable scene card per beat; 2 text fields (title+caption) each.
             for sc in range(1, nscenes + 1):
                 skid = uid(f"s-{tid}-{asp}-{sc}")
+                scimg = f"{MINIO}/template-media/{tid}-{asp}-c{sc}.png"  # per-scene rendered still
                 out.append(
-                    "INSERT INTO content.scenes (id,project_id,key,title,scene_color_svg,default_duration_sec,sort) VALUES ("
-                    f"{q(skid)},{q(pid)},{q('c'+str(sc))},{q('صحنه '+str(sc))},{q(swatch_svg([accent,sec,bg,txt]))},{SCENE_SECONDS},{sc-1});")
+                    "INSERT INTO content.scenes (id,project_id,key,title,image,snapshot_url,scene_color_svg,default_duration_sec,sort) VALUES ("
+                    f"{q(skid)},{q(pid)},{q('c'+str(sc))},{q('صحنه '+str(sc))},{q(scimg)},{q(scimg)},{q(swatch_svg([accent,sec,bg,txt]))},{SCENE_SECONDS},{sc-1});")
                 for pos, (k, title, val) in enumerate(texts[(sc - 1) * 2: sc * 2]):
                     out.append(
                         "INSERT INTO content.scene_content_elements (id,scene_id,key,title,type,default_value,position_in_container,direction_layer_value) VALUES ("
                         f"{q(uid(f'ce-{tid}-{asp}-{k}'))},{q(skid)},{q(k)},{q(title)},'Text',{q(val)},{pos},1);")
         else:
             out.append(
-                "INSERT INTO content.scenes (id,project_id,key,title,scene_color_svg,default_duration_sec,sort) VALUES ("
-                f"{q(sid)},{q(pid)},'c1','صحنه ۱',{q(swatch_svg([accent,sec,bg,txt]))},{dur},0);")
+                "INSERT INTO content.scenes (id,project_id,key,title,image,snapshot_url,scene_color_svg,default_duration_sec,sort) VALUES ("
+                f"{q(sid)},{q(pid)},'c1','صحنه ۱',{q(thumb)},{q(thumb)},{q(swatch_svg([accent,sec,bg,txt]))},{dur},0);")
             for pos, (k, title, val) in enumerate(texts):
                 out.append(
                     "INSERT INTO content.scene_content_elements (id,scene_id,key,title,type,default_value,position_in_container,direction_layer_value) VALUES ("