feat(docs): add OpenAPI API reference from oRPC contract

Generate an OpenAPI 3.1 spec from the oRPC contract at build time
using @orpc/openapi, then use fumadocs-openapi to render interactive
API reference pages grouped by tag (Titles, Episodes, Seasons, etc.).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/package.json

@@ -9,18 +9,21 @@
     "lint": "biome check",
     "format": "biome format --write",
     "check-types": "fumadocs-mdx && next typegen && tsc --noEmit",
+    "generate:api-docs": "bun scripts/generate-api-docs.ts",
     "postinstall": "fumadocs-mdx"
   },
   "dependencies": {
     "@takumi-rs/image-response": "^0.73.0",
     "@vercel/analytics": "^2.0.1",
-    "fumadocs-core": "16.6.17",
-    "fumadocs-mdx": "14.2.10",
-    "fumadocs-ui": "16.6.17",
+    "fumadocs-core": "^16.6.17",
+    "fumadocs-mdx": "^14.2.10",
+    "fumadocs-openapi": "^10.3.18",
+    "fumadocs-ui": "^16.6.17",
     "lucide-react": "^0.577.0",
     "next": "16.1.6",
     "react": "^19.2.4",
     "react-dom": "^19.2.4",
+    "shiki": "^4.0.2",
     "tailwind-merge": "^3.5.0"
   },
   "devDependencies": {