fix: all script resolution uses bundled-first resolveTool()

Replace remaining hardcoded MOSAIC_HOME/tools paths (mosaic-init,
mosaic-ensure-sequential-thinking) and toolScript() with a shared
resolveTool() that checks the npm package first. Every script the
CLI delegates to now picks up the bundled version immediately after
npm upgrade — no mosaic init needed.

Bump @mosaic/mosaic and @mosaic/cli to 0.0.8.

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

packages/mosaic/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@mosaic/mosaic",
-  "version": "0.0.7",
+  "version": "0.0.8",
   "description": "Mosaic agent framework — installation wizard and meta package",
   "type": "module",
   "main": "dist/index.js",