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/bulk-delete.post.ts

@@ -6,7 +6,7 @@ import { commentAttachments, comments, uploads } from '../../db/schema'
 const ID_RE = /^[A-Za-z0-9]{1,16}$/
 
 export default defineEventHandler(async (event) => {
-  await requirePermission(event, 'upload.delete')
+  const actor = await requirePermission(event, 'upload.delete')
   const body = await readBody<{ ids?: unknown }>(event)
   const raw = Array.isArray(body?.ids) ? body.ids : []
   const ids = [...new Set(raw.filter((x): x is string => typeof x === 'string' && ID_RE.test(x)))].slice(0, 200)
@@ -45,5 +45,6 @@ export default defineEventHandler(async (event) => {
     }
   }
   broadcastToAll({ type: 'upload-deleted', ids: found })
+  await logAudit(actor.id, 'bulk_delete_uploads', null, { ids: found, count: found.length })
   return { ok: true, deleted: found.length }
 })