feat(docs): version-bound release documentation served at /docs

Adds a docs pipeline so each release has a version-bound Markdown
document (docs/releases/vX.Y.Z.md) rendered publicly in the app:

- sync-release-docs.mjs copies docs/releases/*.md into the toolrate
  public dir and generates index.json before every dev/build
- /docs lists all releases; /docs/:version renders the sanitized
  Markdown (marked + DOMPurify, typography styles)
- template + workflow documented in docs/README.md
- current release (v0.6.0) documented as the first entry

artifacts/toolrate/package.json

@@ -4,8 +4,8 @@
   "private": true,
   "type": "module",
   "scripts": {
-    "dev": "vite --config vite.config.ts --host 0.0.0.0",
-    "build": "vite build --config vite.config.ts",
+    "dev": "node ../../scripts/src/sync-release-docs.mjs && vite --config vite.config.ts --host 0.0.0.0",
+    "build": "node ../../scripts/src/sync-release-docs.mjs && vite build --config vite.config.ts",
     "serve": "vite preview --config vite.config.ts --host 0.0.0.0",
     "typecheck": "tsc -p tsconfig.json --noEmit"
   },
@@ -54,11 +54,13 @@
     "clsx": "catalog:",
     "cmdk": "1.1.1",
     "date-fns": "4.4.0",
+    "dompurify": "catalog:",
     "embla-carousel-react": "8.6.0",
     "framer-motion": "catalog:",
     "i18next": "26.3.6",
     "input-otp": "1.4.2",
     "lucide-react": "catalog:",
+    "marked": "catalog:",
     "next-themes": "0.4.6",
     "react": "catalog:",
     "react-day-picker": "10.0.1",