feat(connections): add 136 native MCP providers (catalog batch 3)

[staging-tembo]

Summary

Batch 3 of the native MCP catalog expansion: grows the provider catalog from 54 to 190 providers, ships local logo art for providers missing from the Composio CDN, and replaces the hand-maintained Rust OAuth allowlist with one generated from the web catalog.

Commits

1. feat(connections): add 136 native MCP providers (catalog batch 3)

   • Adds 136 entries to web/src/lib/mcp-providers.ts (190 total) with category wiring in connection-categories.ts.

2. fix(connections): ship local logo art for 61 providers missing from Composio CDN

   • Adds PNGs under web/public/mcp-logos/ and maps them in mcp-logo.ts so new catalog entries render with proper logos.

3. refactor(api): generate native OAuth allowlist from web catalog

   • api/src/native_oauth_allowlist.rs is now @generated by web/scripts/gen-native-oauth-allowlist.ts (npm run gen:allowlist) from the TS catalog — eliminating the hand-synced-duplicate-list failure class.
   • The generator validates catalog invariants at generation time: https-only origins, bare-origin format, and no ambiguous shared MCP origins.
   • mcp-providers.allowlist-sync.test.ts now fails only when the generated file is stale; the fix is always "regenerate", never "hand-sync two lists".

Verification

Check	Result
Full web test suite (vitest)	✅ 27 files, 196 tests passed
Allowlist sync test	✅ generated Rust file is current
Generator idempotency (npm run gen:allowlist → clean git status)	✅ no diff
cargo check on api crate	✅ exit 0 (only pre-existing warnings in unrelated files)
Rust native_oauth tests	✅ 3/3 passed
ESLint on changed TS files	✅ clean
Logo cross-check	✅ all 65 files referenced in mcp-logo.ts exist on disk, no orphans
Provider count vs. commit message	✅ exactly 136 slug: entries added

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[staging-tembo]

Requesting review from @ryw who has experience with the following files modified in this PR:

• CHANGELOG.md
• api/src/main.rs
• web/package.json
• api/src/native_oauth.rs
• web/src/lib/mcp-logo.ts
• web/src/lib/docs-content.ts
• web/src/lib/mcp-providers.ts
• docs/src/content/docs/connections.md
• web/src/lib/connection-categories.ts
• web/src/lib/mcp-providers.allowlist-sync.test.ts