feat: Stage 1 — backend and frontend scaffolding

Backend (tasks 1.1, 1.5–1.8):
- pyproject.toml with FastAPI, Pydantic v2, aiosqlite, APScheduler 3.x,
  structlog, bcrypt; ruff + mypy strict configured
- Pydantic Settings (BANGUI_ prefix env vars, fail-fast validation)
- SQLite schema: settings, sessions, blocklist_sources, import_log;
  WAL mode + foreign keys; idempotent init_db()
- FastAPI app factory with lifespan (DB, aiohttp session, scheduler),
  CORS, unhandled-exception handler, GET /api/health
- Fail2BanClient: async Unix-socket wrapper using run_in_executor,
  custom error types, async context manager
- Utility modules: ip_utils, time_utils, constants
- 47 tests; ruff 0 errors; mypy --strict 0 errors

Frontend (tasks 1.2–1.4):
- Vite + React 18 + TypeScript strict; Fluent UI v9; ESLint + Prettier
- Custom brand theme (#0F6CBD, WCAG AA contrast) with light/dark variants
- Typed fetch API client (ApiError, get/post/put/del) + endpoints constants
- tsc --noEmit 0 errors

frontend/eslint.config.ts

@@ -0,0 +1,28 @@
+import js from "@eslint/js";
+import tseslint from "typescript-eslint";
+import reactHooks from "eslint-plugin-react-hooks";
+import prettierConfig from "eslint-config-prettier";
+
+export default tseslint.config(
+  { ignores: ["dist"] },
+  {
+    extends: [js.configs.recommended, ...tseslint.configs.strictTypeChecked],
+    files: ["**/*.{ts,tsx}"],
+    languageOptions: {
+      parserOptions: {
+        project: ["./tsconfig.json", "./tsconfig.node.json"],
+        tsconfigRootDir: import.meta.dirname,
+      },
+    },
+    plugins: {
+      "react-hooks": reactHooks,
+    },
+    rules: {
+      ...reactHooks.configs.recommended.rules,
+      "@typescript-eslint/no-explicit-any": "error",
+      "@typescript-eslint/explicit-function-return-type": "warn",
+      "@typescript-eslint/no-unused-vars": ["error", { argsIgnorePattern: "^_" }],
+    },
+  },
+  prettierConfig,
+);