Fix image deletion: per-tag delete, repository delete, daily GC.

- Deleting a tag now untags only that tag; the manifest is removed only when
  no other tag references the same digest (previously deleting by digest also
  removed every sibling tag).
- Add repository deletion. The registry API cannot drop a repository from the
  catalog, so empty repositories stayed in the UI forever with nothing left to
  delete. The app now mounts registry storage and removes the repository's
  metadata directories after deleting its manifests.
- Run `registry garbage-collect` daily (GC_HOUR_UTC) so deleted blobs free disk.
- Disable Watchtower for the locally built app image.

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

app/server/api/repositories/index.delete.ts

@@ -0,0 +1,27 @@
+import { z } from 'zod'
+
+const bodySchema = z.object({
+  name: z.string().min(1),
+})
+
+export default defineEventHandler(async (event) => {
+  const session = await requireSession(event)
+  await ensureBootstrap()
+
+  const { name } = bodySchema.parse(await readBody(event))
+  await requireDeletePermission(session, name)
+
+  // Delete manifests through the API first so blobs become unreferenced for GC
+  const tags = await listTags(name)
+  const digests = new Set<string>()
+  for (const tag of tags) {
+    const digest = await getManifestDigest(name, tag)
+    if (digest) digests.add(digest)
+  }
+  for (const digest of digests) {
+    await deleteManifest(name, digest)
+  }
+
+  await removeRepositoryFromStorage(name)
+  return { ok: true, name, deletedTags: tags.length }
+})