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/ui/src/lib/i18n/messages/en.settings.ts

@@ -897,16 +897,26 @@ export const settingsDict = {
   'settings.skills.catalog.page.mode.manual': 'Manual',
   'settings.skills.catalog.page.mode.external': 'External',
   'settings.skills.catalog.page.title': 'Skills Catalog',
+  'settings.skills.catalog.page.subtitle': 'Install ready-made skills from curated repositories, or add your own source.',
+  'settings.skills.catalog.page.section.sources': 'Sources',
+  'settings.skills.catalog.page.searchAllPlaceholder': 'Search skills across all sources…',
+  'settings.skills.catalog.page.search.clear': 'Clear search',
+  'settings.skills.catalog.page.source.skillsCount': '{count} skills',
+  'settings.skills.catalog.page.source.stars': '{count} stars',
+  'settings.skills.catalog.page.source.updated': 'Updated {time}',
+  'settings.skills.catalog.page.source.addOwnTitle': 'Add your own source',
+  'settings.skills.catalog.page.source.addOwnDescription': 'Any Git repository with skills',
+  'settings.skills.catalog.page.source.viewRepo': 'Open repository on GitHub',
+  'settings.skills.catalog.page.skill.viewOnGithub': 'View skill on GitHub',
+  'settings.skills.catalog.page.list.searchTitle': 'Search results',
   'settings.skills.catalog.page.section.sourceRepository': 'Source Repository',
   'settings.skills.catalog.page.field.selectSourcePlaceholder': 'Select source',
   'settings.skills.catalog.page.actions.refreshTitle': 'Refresh',
   'settings.skills.catalog.page.actions.removeCatalogTitle': 'Remove Catalog',
   'settings.skills.catalog.page.actions.addCatalog': 'Add Catalog',
   'settings.skills.catalog.page.actions.removeCatalog': 'Remove Catalog',
-  'settings.skills.catalog.page.actions.loadMoreSkills': 'Load More Skills',
   'settings.skills.catalog.page.loading.catalog': 'Loading...',
   'settings.skills.catalog.page.loading.skills': 'Loading skills...',
-  'settings.skills.catalog.page.loading.more': 'Loading...',
   'settings.skills.catalog.page.foundCount': '{count} skill(s) found',
   'settings.skills.catalog.page.error.catalogTitle': 'Catalog error',
   'settings.skills.catalog.page.empty.noSkillsTitle': 'No skills found',
@@ -914,7 +924,6 @@ export const settingsDict = {
   'settings.skills.catalog.page.badge.installed': 'installed ({scope})',
   'settings.skills.catalog.page.badge.notInstallable': 'not installable',
   'settings.skills.catalog.page.badge.unknown': 'unknown',
-  'settings.skills.catalog.page.byOwnerPrefix': 'by',
   'settings.skills.catalog.page.removeDialog.title': 'Remove Catalog',
   'settings.skills.catalog.page.removeDialog.description': 'Are you sure you want to remove this catalog?',
   'settings.openchamber.passkeys.title': 'Passkeys',