chore(tooling): oxlint + oxfmt frontend, lefthook gate, govulncheck (#21)

- apps/frontend: oxlint 1.85 (typescript/unicorn/oxc — no react rules,
  SolidJS), oxfmt scripts; lint script now oxlint && tsc --noEmit
- backend: gofmt; bump x/text 0.39.0, quic-go 0.59.1, pgx 5.9.2
  (govulncheck 0 reachable vulns, was 3)
- ci: go vet + govulncheck in Go job (frontend job already gates via
  lint:frontend)
- lefthook pre-push: frontend lint + gofmt + vet/test + gitleaks

Authored By: TDvorak <[email protected]>

Generated with [Devin](https://devin.ai)

Co-authored-by: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/frontend/package.json

@@ -7,7 +7,9 @@
     "dev": "vite",
     "build": "tsc -b && vite build",
     "preview": "vite preview",
-    "lint": "tsc --noEmit"
+    "lint": "oxlint && tsc --noEmit",
+    "format": "oxfmt",
+    "format:check": "oxfmt --check"
   },
   "dependencies": {
     "@bookra/api-client": "0.1.0",
@@ -20,6 +22,8 @@
   "devDependencies": {
     "@types/node": "^24.0.0",
     "autoprefixer": "^10.4.20",
+    "oxfmt": "^0.70.0",
+    "oxlint": "^1.85.0",
     "postcss": "^8.5.1",
     "tailwindcss": "^3.4.17",
     "typescript": "^5.8.3",