Replace hand-written TMDB types with openapi-fetch + generated schema

- Add `openapi-fetch` dependency; generate `lib/tmdb/schema.d.ts` from
  TMDB's OpenAPI spec and delete `lib/tmdb/types.ts`
- Rewrite `lib/tmdb/client.ts` to use the typed fetch client against
  the generated schema, exporting `TmdbMovieDetails`, `TmdbTvDetails`,
  `TmdbVideo`, and `TmdbGenre` directly
- Fix null-safety across services (`credits`, `availability`,
  `metadata`, `person`, `webhooks`) and call sites (explore page,
  search route, explore actions) to handle optional fields produced
  by the stricter generated types
- Update `metadata.ts` and `metadata.test.ts` to import shared types
  from `@/lib/tmdb/client` instead of the removed `types.ts`
- Exclude `lib/tmdb/schema.d.ts` from Biome linting

bun.lock

@@ -22,6 +22,7 @@
         "motion": "12.35.1",
         "next": "16.1.6",
         "node-vibrant": "4.0.4",
+        "openapi-fetch": "0.17.0",
         "react": "19.2.4",
         "react-day-picker": "9.14.0",
         "react-dom": "19.2.4",
@@ -1194,6 +1195,10 @@
 
     "open": ["open@11.0.0", "", { "dependencies": { "default-browser": "^5.4.0", "define-lazy-prop": "^3.0.0", "is-in-ssh": "^1.0.0", "is-inside-container": "^1.0.0", "powershell-utils": "^0.1.0", "wsl-utils": "^0.3.0" } }, "sha512-smsWv2LzFjP03xmvFoJ331ss6h+jixfA4UUV/Bsiyuu4YJPfN+FIQGOIiv4w9/+MoHkfkJ22UIaQWRVFRfH6Vw=="],
 
+    "openapi-fetch": ["openapi-fetch@0.17.0", "", { "dependencies": { "openapi-typescript-helpers": "^0.1.0" } }, "sha512-PsbZR1wAPcG91eEthKhN+Zn92FMHxv+/faECIwjXdxfTODGSGegYv0sc1Olz+HYPvKOuoXfp+0pA2XVt2cI0Ig=="],
+
+    "openapi-typescript-helpers": ["openapi-typescript-helpers@0.1.0", "", {}, "sha512-OKTGPthhivLw/fHz6c3OPtg72vi86qaMlqbJuVJ23qOvQ+53uw1n7HdmkJFibloF7QEjDrDkzJiOJuockM/ljw=="],
+
     "ora": ["ora@8.2.0", "", { "dependencies": { "chalk": "^5.3.0", "cli-cursor": "^5.0.0", "cli-spinners": "^2.9.2", "is-interactive": "^2.0.0", "is-unicode-supported": "^2.0.0", "log-symbols": "^6.0.0", "stdin-discarder": "^0.2.2", "string-width": "^7.2.0", "strip-ansi": "^7.1.0" } }, "sha512-weP+BZ8MVNnlCm8c0Qdc1WSWq4Qn7I+9CJGm7Qali6g44e/PUzbjNqJX5NJ9ljlNMosfJvg1fKEGILklK9cwnw=="],
 
     "outvariant": ["outvariant@1.4.3", "", {}, "sha512-+Sl2UErvtsoajRDKCE5/dBz4DIvHXQQnAxtQTF04OJxY0+DyZXSo5P5Bb7XYWOh81syohlYL24hbDwxedPUJCA=="],