docs(website): audit and fix all stale claims on doc site

- Rewrite homepage: drop unverified benchmark claims (42% savings, 99% fewer
  tokens), drop "context bundling" framing (dev_plan removed), replace with
  factual descriptions of what tools actually do
- Fix LanceDB → Antfly in dev-search, dev-map, dev-health, dev-status tool pages
- Fix all-MiniLM-L6-v2 → BAAI/bge-small-en-v1.5 in docs/index and dev-search
- Fix dev explore → dev search --similar-to in cli.mdx
- Add Antfly install to quick start (was missing)
- Fix test count to 1,600+

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: prosdev