Implement the 006-pre-commit-gate feature that enforces a pre-commit quality gate using Lefthook to run pnpm check before every commit

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

package.json

@@ -3,10 +3,12 @@
 	"packageManager": "pnpm@10.6.0",
 	"devDependencies": {
 		"@biomejs/biome": "2.0.0",
+		"lefthook": "^1.11.0",
 		"typescript": "^5.8.0",
 		"vitest": "^3.0.0"
 	},
 	"scripts": {
+		"prepare": "lefthook install",
 		"format": "biome format --write .",
 		"format:check": "biome format .",
 		"lint": "biome lint .",