chore(release): clean dist/ before tsc to prevent stale artifacts

tsc does not remove output files when their source is deleted or
renamed, so successive refactors leave bit-rotted files in dist/. The
2.0.0 tarball still shipped dist/schema.js (pre-split monolith),
dist/tools/domains.js, dist/tools/account.js, and dist/tools/generate-
domains.js -- all dead weight that no live code imports.

Add a portable clean step (node -e fs.rmSync) and run it from a
prebuild hook so every build starts from an empty dist/. No new
dependency.

Impact on the 2.0.0 tarball:
- files:        112 -> 100
- packed size:  54.4 KB -> 42.8 KB
- unpacked:     289.1 KB -> 194.7 KB
- brotli size:  25.65 KB -> 18.53 KB (size-limit)

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

Author: joachimBrindeau

package.json

@@ -30,6 +30,8 @@
   },
   "scripts": {
     "start": "tsx src/index.ts",
+    "clean": "node -e \"require('fs').rmSync('dist',{recursive:true,force:true})\"",
+    "prebuild": "npm run clean",
     "build": "tsc",
     "dev": "tsx watch src/index.ts",
     "test": "vitest run",