Add library build pipeline and token alignment report

- Configure Vite library mode to export MUI theme as plain JS
- Add tsconfig.build.json for declaration generation
- Add package.json exports for theme, Tailwind config, and tokens
- Create src/index.ts as library entry point
- Document token alignment between design system and production
  including colour mapping, flagged conflicts, and breakpoint alignment

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tsconfig.build.json

@@ -0,0 +1,12 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "noEmit": false,
+    "declaration": true,
+    "emitDeclarationOnly": true,
+    "outDir": "dist",
+    "noUnusedLocals": false,
+    "noUnusedParameters": false
+  },
+  "include": ["src/index.ts", "src/theme"]
+}