chore: sync MCP server work + add OAuth org-binding migration

Accumulated local changes across the nerve center, context manager, local
search, MCP/server entrypoints, and CLI, plus refreshed docs, eslint config,
and tests. Removes stale temp-state test fixtures.

Adds supabase migration 0008_oauth_org_binding.sql (org binding for the OAuth
flow) and updates .gitignore to track supabase migrations while keeping schema
dumps and CLI temp files ignored.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>