Keep thread navigation within the originating upload list

Record where an upload was opened from in a new useUploadNavContext
state. When a tile is clicked on a user profile, the thread page passes
that context to the upload detail API, which scopes the newer/older
neighbors to that user's uploads. Arrow clicks reseed the context for
the next thread, so the chain stays within the source list without a
URL parameter. Threads opened directly (notification, reload) fall back
to the global order. The breadcrumb reads the same context and shows
the profile path for profile-originated threads, now including the
thread id in the final crumb.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

server/api/uploads/[id].get.ts

@@ -55,8 +55,13 @@ export default defineEventHandler(async (event) => {
     .where(eq(comments.uploadId, id))
     .orderBy(asc(comments.createdAt))
 
-  // Nachbarn in Grid-Reihenfolge (createdAt desc, id desc als Tiebreak)
+  // Nachbarn in Grid-Reihenfolge (createdAt desc, id desc als Tiebreak).
+  // Kontext ?from=/user/<id> scopt die Navigation auf die Uploads dieses
+  // Nutzers — so durchläuft man vom Profil aus nur dessen Uploads
   const sessionUser = await getSessionUser(event)
+  const from = String(getQuery(event).from ?? '')
+  const contextUserId = /^\/user\/(\d+)$/.exec(from)?.[1]
+  const scopedToUser = contextUserId ? eq(uploads.userId, Number(contextUserId)) : undefined
   const commentIds = commentRows.map(c => c.id)
   const [reactionRows, uploadReactionRows, favRows, newerRows, olderRows, tagRows, attachmentRows, subscriptionRows] = await Promise.all([
     commentIds.length
@@ -91,18 +96,24 @@ export default defineEventHandler(async (event) => {
     db
       .select({ id: uploads.id })
       .from(uploads)
-      .where(or(
-        gt(uploads.createdAt, upload.createdAt),
-        and(eq(uploads.createdAt, upload.createdAt), gt(uploads.id, upload.id)),
+      .where(and(
+        or(
+          gt(uploads.createdAt, upload.createdAt),
+          and(eq(uploads.createdAt, upload.createdAt), gt(uploads.id, upload.id)),
+        ),
+        scopedToUser,
       ))
       .orderBy(asc(uploads.createdAt), asc(uploads.id))
       .limit(1),
     db
       .select({ id: uploads.id })
       .from(uploads)
-      .where(or(
-        lt(uploads.createdAt, upload.createdAt),
-        and(eq(uploads.createdAt, upload.createdAt), lt(uploads.id, upload.id)),
+      .where(and(
+        or(
+          lt(uploads.createdAt, upload.createdAt),
+          and(eq(uploads.createdAt, upload.createdAt), lt(uploads.id, upload.id)),
+        ),
+        scopedToUser,
       ))
       .orderBy(desc(uploads.createdAt), desc(uploads.id))
       .limit(1),