Fix turbo watch command syntax

Use `turbo watch build` instead of `turbo build --watch`.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

package.json

@@ -8,7 +8,7 @@
   "scripts": {
     "dev": "turbo dev",
     "build": "turbo build",
-    "build:watch:packages": "turbo build --watch --filter=./packages/*",
+    "build:watch:packages": "turbo watch build --filter=./packages/*",
     "lint": "biome check",
     "lint:fix": "biome check --write --unsafe",
     "typecheck": "turbo typecheck",