fix(skills-hub): show every catalog source on /docs/skills (skills.sh, ClawHub, browse.sh, OpenAI, …) (#32336)

The Skills Hub page was stuck on a stale Feb 25 snapshot, showing only Built-in
+ Optional + Anthropic + LobeHub. The unified index already has 2078 skills
from skills.sh / ClawHub / LobeHub / GitHub taps / Claude Marketplace, and
BrowseShSource adds another ~330 — none of it was reaching the page.

Changes:

- website/scripts/extract-skills.py: read website/static/api/skills-index.json
  (the unified multi-source catalog, rebuilt twice daily) as the canonical
  external source. Keep the legacy skills/index-cache/ fallback for offline
  builds. Add friendly per-source labels (skills.sh, ClawHub, browse.sh,
  OpenAI, HuggingFace, Anthropic, LobeHub, etc.) and per-entry installCmd.
- website/src/pages/skills/index.tsx: add source pills + ordering for the 11
  new sources; render installCmd from the index entry.
- website/scripts/prebuild.mjs: when no local skills-index.json exists, fetch
  the live one from hermes-agent.nousresearch.com so local 'npm run build'
  matches production without burning GitHub API quota.
- scripts/build_skills_index.py: crawl BrowseShSource so browse.sh entries
  land in the unified index. Adjust source_order.
- tools/skills_hub.py: GitHubSource.DEFAULT_TAPS — openai/skills moved its
  skills into skills/.curated/ and skills/.system/, so add both as explicit
  taps (the listing code skips dotted dirs by design). Drop
  VoltAgent/awesome-agent-skills (README-only, no SKILL.md files) and
  MiniMax-AI/cli (singular skill, not a tap directory). Net effect: github
  source jumps from 83 → 143 skills, with OpenAI properly included.
- .github/workflows/deploy-site.yml: build the unified index BEFORE running
  extract-skills.py — previous order meant extract-skills always fell back
  to the legacy cache. Drop the 'skip if file exists' guard; the file is
  gitignored and must be rebuilt every deploy.
- .github/workflows/skills-index.yml: drop the broken 'deploy-with-index'
  job (it cp'd 'landingpage/\*' which no longer exists, failing every cron
  run since the landingpage move). Replace it with a workflow_dispatch
  trigger of deploy-site.yml so the index refresh still reaches production
  on schedule.
- website/docs/user-guide/features/skills.md: drop VoltAgent from the
  default-taps doc list to match the code.

Before: 695 skills (Built-in 90, Optional 84, Anthropic 16, LobeHub 505).
After:  2168 skills across 9 source pills, including the 1212 skills.sh
        entries the user expected to see.

website/docs/user-guide/features/skills.md

@@ -467,7 +467,6 @@ Default taps (browsable without any setup):
 - [openai/skills](https://github.com/openai/skills)
 - [anthropics/skills](https://github.com/anthropics/skills)
 - [huggingface/skills](https://github.com/huggingface/skills)
-- [VoltAgent/awesome-agent-skills](https://github.com/VoltAgent/awesome-agent-skills)
 - [garrytan/gstack](https://github.com/garrytan/gstack)
 
 - Example: