Add audit log for moderation and admin actions

New audit_log table records actor, action, target and a JSON snapshot
of the details, so entries stay readable after the target is deleted;
the actor is set to NULL when the user is removed. logAudit() is called
from upload delete (single and bulk), comment delete, tag removal, role
create/delete, role permission changes, role assign/revoke and MOTD
updates. Logging failures only warn and never fail the action itself.

The admin page gets an audit card behind the new audit.view permission
with action filter, click-to-filter by user, readable summaries per
action and server-side pagination. Action catalog lives in
shared/utils/audit.ts, labels under admin.auditActions (de/en).

Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

server/api/uploads/[id]/tags.put.ts

@@ -60,5 +60,8 @@ export default defineEventHandler(async (event) => {
     await db.insert(uploadTags).values(tagRows.map(t => ({ uploadId: id, tagId: t.id })))
   }
 
+  if (removed.length) {
+    await logAudit(user.id, 'remove_tags', { type: 'upload', id }, { removed, isUploader: upload.userId === user.id })
+  }
   return { tags: tagRows.map(t => t.name).sort() }
 })