feat(skills): curated GitHub catalog redesign (#3016)

* feat(skills): remove ClawHub catalog integration

Drop the ClawHub registry as a skills catalog source across web server,
shared UI, VS Code, docs, and locales. The catalog now serves git-based
sources only: the curated Anthropic repo and user-defined repositories.
Also removes the now-unused adm-zip dependency.

* feat(skills): redesign catalog around curated GitHub repositories

Replace the single-source dropdown with a card grid of curated GitHub
repositories (Anthropic, OpenAI, Cursor pstack/skills, Matt Pocock) plus
user-defined sources. Source cards show skill counts, GitHub stars, and
last-updated time; a global search covers all loaded sources.

Server: curated sources gain GitHub repo metadata (stars, pushed_at)
fetched best-effort with a 3-hour in-memory and on-disk cache; scans
run through a concurrency-limited, deduplicated cache with 3-hour TTL
persisted across restarts. Refresh still bypasses the cache.

Shared UI: source cards, global search with clear button, per-skill
GitHub links, install/installed states. VS Code curated list updated
to match. All new copy translated across 12 locales.

* fix(skills): address catalog review findings

- GitHub metadata fetch timeout drops to 1.5s (under the catalog
  client's 3s deadline) and failed lookups cache briefly (5 min) so
  repeated catalog loads do not re-hit a failing API.
- Disk cache files are written with owner-only permissions (0o600);
  rename preserves the mode.
- loadSource deduplicates concurrent in-flight requests per source and
  the shared isLoadingSource flag now clears only when the last active
  source load finishes.

packages/web/server/lib/opencode/skill-routes.test.js

@@ -69,14 +69,11 @@ const startSkillsApp = ({ projectRoot }) => {
     SKILL_DIR,
     getCuratedSkillsSources: () => [],
     getCacheKey: () => 'k',
-    getCachedScan: () => null,
-    setCachedScan: () => {},
+    scanWithCache: async (_key, loader) => loader(),
     parseSkillRepoSource: () => ({ ok: false }),
     scanSkillsRepository: async () => ({ ok: false }),
     installSkillsFromRepository: async () => ({ ok: false }),
-    scanClawdHubPage: async () => ({ ok: false }),
-    installSkillsFromClawdHub: async () => ({ ok: false }),
-    isClawdHubSource: () => false,
+    fetchGitHubRepoMetas: async () => ({}),
     getProfiles: () => [],
     getProfile: () => null,
   });