feat: implement Phase 2 (Go Agent) and Phase 3 (React Frontend MVP)

Phase 2 - Go Agent Core:
- gRPC client with exponential backoff reconnect logic
- Command executor (PowerShell/sh cross-platform)
- Proto stubs regenerated with module= option (correct output path)
- gRPC upgraded to v1.79.3 (BidiStreamingClient support)

Phase 3 - React Frontend MVP:
- Vite + React 18 + TypeScript setup with Tailwind CSS v4
- TanStack Query for data fetching, API client + TypeScript types
- Dashboard page: stats cards (agents/status/tickets) + sortable agents table
- Agent detail page: CPU/RAM charts (Recharts), disk usage, shell command executor
- Tickets page: CRUD with modals, filters, sortable table
- Dark mode with CSS custom properties

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

Frontend/tsconfig.node.json

@@ -0,0 +1,26 @@
+{
+  "compilerOptions": {
+    "tsBuildInfoFile": "./node_modules/.tmp/tsconfig.node.tsbuildinfo",
+    "target": "ES2023",
+    "lib": ["ES2023"],
+    "module": "ESNext",
+    "types": ["node"],
+    "skipLibCheck": true,
+
+    /* Bundler mode */
+    "moduleResolution": "bundler",
+    "allowImportingTsExtensions": true,
+    "verbatimModuleSyntax": true,
+    "moduleDetection": "force",
+    "noEmit": true,
+
+    /* Linting */
+    "strict": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "erasableSyntaxOnly": true,
+    "noFallthroughCasesInSwitch": true,
+    "noUncheckedSideEffectImports": true
+  },
+  "include": ["vite.config.ts"]
+}