fix: Phase 0 verification — passWithNoTests, prettierignore (P0-009)

Add --passWithNoTests to all vitest test scripts so packages without
test files don't fail CI. Add .prettierignore for auto-generated files
(next-env.d.ts, dist, drizzle, .next). All quality gates now pass:
typecheck, lint, format:check, test, build (18/18 packages).

Closes #9

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

packages/auth/package.json

@@ -14,7 +14,7 @@
     "build": "tsc",
     "lint": "eslint src",
     "typecheck": "tsc --noEmit",
-    "test": "vitest run"
+    "test": "vitest run --passWithNoTests"
   },
   "devDependencies": {
     "@types/node": "^22.0.0",