security: rate-limit route handlers that perform authorization

[davidcrowe]

Closes two CodeQL js/missing-rate-limiting alerts.

Findings addressed

#51 — apps/gateway-server/src/app.ts:169 (regression from PR #21)

The /protected pipeline runs identifiabl → limitabl → transformabl. The per-identity limiter (limitabl) can't rate-limit invalid JWT attempts — it needs req.user.sub to derive its key, and unauth requests fall back to IP which partitions poorly. An attacker can flood the endpoint with garbage JWTs and exhaust the RSA verify path before limitabl sees them.

Fix: added a generic IP-keyed rateLimit in front of identifiabl. Ceiling is limit * 10 — well above normal traffic; the real per-user cap is still limitabl downstream. Same pattern the /tools pipeline in this file already uses (toolsRateLimiter).

#47 — packages/proxyabl/src/tool-gateway.ts:1237 (pre-existing)

The proxy catch-all route did verifyBearer with no rate limiter. Applied the existing toolLimiter that's already defined in the same file for other routes.

Test plan

• npm run build — clean
• npx vitest run — 159/159
• gitleaks clean
• CodeQL should re-scan after merge and drop both alerts

Notes

• No package version bumps; apps/gateway-server is not published, and the proxyabl change is a drop-in middleware composition with no API surface change.
• Stale Dependabot vite alerts (chore(deps-dev): bump minimatch from 3.1.2 to 3.1.5 #16, chore(deps): bump express-rate-limit from 8.2.1 to 8.2.2 #17, chore(deps-dev): bump picomatch from 4.0.3 to 4.0.4 #18) are false positives — lockfile has vite 6.4.2 + 7.2.7; the CVEs are for >=8.0.0, <=8.0.4. Not addressed here; will auto-close on next scan or can be dismissed.