fix: resolve TODO.md security/perf/test-coverage backlog

Fixes the 13-item codebase health scan backlog: wraps meal-plan
generation in a transaction, adds missing userId/GIN indexes, fixes
an IPv6-parsing gap in the webhook SSRF guard (and an identical
duplicated bug in the AI URL-import path, now consolidated onto one
implementation), paginates the collections list, dedupes the AI
recipe Zod schemas, wires up Stripe tier sync, rate-limits AI key
rotation, gets `pnpm typecheck` actually working, and adds test
coverage for the previously-untested admin/webhooks routes.

Two flagged issues (collection removeRecipeId IDOR, tier-limit race)
turned out to already be fixed/non-issues on inspection — noted in
TODO.md rather than silently dropped.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

packages/api-types/package.json

@@ -7,6 +7,9 @@
   "exports": {
     ".": "./src/index.ts"
   },
+  "scripts": {
+    "typecheck": "tsc --noEmit"
+  },
   "dependencies": {
     "zod": "^3.25.67"
   },