feat(player): let editors upload subtitles for a version

Subtitle tracks hang off a version rather than off a video, because re-editing a cut shifts every cue. The file
always lands in our own S3-compatible storage whatever hosts the video, so a Bunny-hosted cut and an R2 one take the
same path: both already play through our own video element, so a track element is all it takes.

Uploads are normalised before they are stored. Whatever arrives, SRT or WebVTT, is parsed into cues and
re-serialised as a canonical WebVTT file, and anything we did not understand is dropped rather than passed through.
That is what makes it safe to serve a user-supplied text file from our own origin. Files saved out of Windows
editors are decoded as windows-1254 or windows-1252 when they are not valid UTF-8, rather than refused.

A YouTube version cannot carry an uploaded track, so the same CC menu drives YouTube's own captions through the
iframe module API. The embed hides YouTube's controls, so until now those captions were unreachable even when the
video had them.

Uploading and deleting take the editor permission rather than the commenter one: a subtitle is part of the
delivered cut, not a comment attachment.

lib/r2-cleanup.ts

@@ -3,6 +3,7 @@ import { r2Client, R2_BUCKET_NAME } from '@/lib/r2';
 import { db } from '@/lib/db';
 import { runWithConcurrency } from '@/lib/async-pool';
 import { videoProxyPathToObjectKey } from '@/lib/video-upload-validation';
+import { subtitleProxyPathToObjectKey } from '@/lib/subtitle-validation';
 import { logError } from '@/lib/logger';
 
 /** The path prefix for images served by the upload API. */
@@ -34,7 +35,7 @@ export function mediaUrlToKey(url: string): string | null {
     return filename ? `images/${filename}` : null;
   }
 
-  return videoProxyPathToObjectKey(url);
+  return subtitleProxyPathToObjectKey(url) ?? videoProxyPathToObjectKey(url);
 }
 
 /**
@@ -82,7 +83,7 @@ export async function deleteMediaFilesBestEffort(mediaUrls: string[]): Promise<R
  * Collect all media URLs from comments under a given video (all versions).
  */
 export async function collectVideoMediaUrls(videoId: string): Promise<string[]> {
-  const [comments, assets, versions] = await Promise.all([
+  const [comments, assets, versions, subtitles] = await Promise.all([
     db.comment.findMany({
       where: {
         OR: [{ voiceUrl: { not: null } }, { images: { some: {} } }],
@@ -101,6 +102,10 @@ export async function collectVideoMediaUrls(videoId: string): Promise<string[]>
       where: { videoParentId: videoId, providerId: 'r2' },
       select: { originalUrl: true, thumbnailUrl: true },
     }),
+    db.videoSubtitle.findMany({
+      where: { version: { videoParentId: videoId } },
+      select: { sourceUrl: true },
+    }),
   ]);
   const urls: string[] = [];
   comments.forEach((c) => {
@@ -114,6 +119,9 @@ export async function collectVideoMediaUrls(videoId: string): Promise<string[]>
     if (version.originalUrl) urls.push(version.originalUrl);
     if (version.thumbnailUrl) urls.push(version.thumbnailUrl);
   });
+  subtitles.forEach((subtitle) => {
+    if (subtitle.sourceUrl) urls.push(subtitle.sourceUrl);
+  });
   return urls;
 }
 
@@ -121,7 +129,7 @@ export async function collectVideoMediaUrls(videoId: string): Promise<string[]>
  * Collect all media URLs from comments under all videos in a project.
  */
 export async function collectProjectMediaUrls(projectId: string): Promise<string[]> {
-  const [comments, assets, versions] = await Promise.all([
+  const [comments, assets, versions, subtitles] = await Promise.all([
     db.comment.findMany({
       where: {
         OR: [{ voiceUrl: { not: null } }, { images: { some: {} } }],
@@ -140,6 +148,10 @@ export async function collectProjectMediaUrls(projectId: string): Promise<string
       where: { providerId: 'r2', video: { projectId } },
       select: { originalUrl: true, thumbnailUrl: true },
     }),
+    db.videoSubtitle.findMany({
+      where: { version: { video: { projectId } } },
+      select: { sourceUrl: true },
+    }),
   ]);
   const urls: string[] = [];
   comments.forEach((c) => {
@@ -153,6 +165,9 @@ export async function collectProjectMediaUrls(projectId: string): Promise<string
     if (version.originalUrl) urls.push(version.originalUrl);
     if (version.thumbnailUrl) urls.push(version.thumbnailUrl);
   });
+  subtitles.forEach((subtitle) => {
+    if (subtitle.sourceUrl) urls.push(subtitle.sourceUrl);
+  });
   return urls;
 }
 
@@ -160,7 +175,7 @@ export async function collectProjectMediaUrls(projectId: string): Promise<string
  * Collect all media URLs from comments under all projects in a workspace.
  */
 export async function collectWorkspaceMediaUrls(workspaceId: string): Promise<string[]> {
-  const [comments, assets, versions] = await Promise.all([
+  const [comments, assets, versions, subtitles] = await Promise.all([
     db.comment.findMany({
       where: {
         OR: [{ voiceUrl: { not: null } }, { images: { some: {} } }],
@@ -179,6 +194,10 @@ export async function collectWorkspaceMediaUrls(workspaceId: string): Promise<st
       where: { providerId: 'r2', video: { project: { workspaceId } } },
       select: { originalUrl: true, thumbnailUrl: true },
     }),
+    db.videoSubtitle.findMany({
+      where: { version: { video: { project: { workspaceId } } } },
+      select: { sourceUrl: true },
+    }),
   ]);
   const urls: string[] = [];
   comments.forEach((c) => {
@@ -192,6 +211,9 @@ export async function collectWorkspaceMediaUrls(workspaceId: string): Promise<st
     if (version.originalUrl) urls.push(version.originalUrl);
     if (version.thumbnailUrl) urls.push(version.thumbnailUrl);
   });
+  subtitles.forEach((subtitle) => {
+    if (subtitle.sourceUrl) urls.push(subtitle.sourceUrl);
+  });
   return urls;
 }