feat(M1): Project scaffolding, DB schema, core infrastructure

- Initialize Rust workspace with 7 crates (pm-web, pm-worker, pm-core,
  pm-agent-client, pm-auth, pm-ca, pm-reports)
- React + TypeScript + Vite + MUI frontend scaffold
- Full PostgreSQL schema: all 17 tables with indexes and constraints
- pm-core: config (TOML+env), db (SQLx pool + migrations), error
  (unified AppError + JSON envelope), request_id (ULID middleware),
  logging (tracing JSON/pretty)
- pm-web: Axum skeleton, /status/health endpoint, static file serving
- pm-worker: Tokio skeleton, heartbeat writer, schema version check
- Embedded sqlx migrations with advisory lock (single-writer)
- systemd unit files, setup.sh, build-frontend.sh
- config.example.toml with all configuration keys
- docs/runbooks/restore.md
- cargo check passes with zero warnings

Closes M1.

frontend/package.json

@@ -0,0 +1,34 @@
+{
+  "name": "patch-manager-ui",
+  "private": true,
+  "version": "0.1.0",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "tsc && vite build",
+    "preview": "vite preview",
+    "lint": "eslint . --ext ts,tsx --report-unused-disable-directives --max-warnings 0",
+    "type-check": "tsc --noEmit"
+  },
+  "dependencies": {
+    "@emotion/react": "^11.14.0",
+    "@emotion/styled": "^11.14.0",
+    "@mui/icons-material": "^7.0.0",
+    "@mui/material": "^7.0.0",
+    "axios": "^1.9.0",
+    "react": "^19.0.0",
+    "react-dom": "^19.0.0",
+    "react-router-dom": "^7.5.3",
+    "zustand": "^5.0.3"
+  },
+  "devDependencies": {
+    "@types/react": "^19.0.0",
+    "@types/react-dom": "^19.0.0",
+    "@typescript-eslint/eslint-plugin": "^8.30.0",
+    "@typescript-eslint/parser": "^8.30.0",
+    "@vitejs/plugin-react": "^4.4.1",
+    "eslint": "^9.24.0",
+    "typescript": "^5.8.3",
+    "vite": "^6.3.3"
+  }
+}