Add project scaffolding and build configuration

Initialize the session-viewer project — a tool for browsing, filtering,
redacting, and exporting Claude Code session logs as self-contained HTML.

Scaffolding includes:
- package.json with Express server + React client dual-stack setup,
  dev/build/test/lint/typecheck scripts, and a CLI bin entry point
- TypeScript configs: base tsconfig.json (ESNext, bundler resolution,
  strict, react-jsx) and tsconfig.server.json extending it for the
  Express server compilation target
- Vite config: React plugin, Tailscale-aware dev server on :3847 with
  API proxy to :3848, client build output to dist/client
- Vitest config: node environment, test discovery from tests/unit and
  src/client/components
- ESLint flat config: typescript-eslint recommended, unused-vars with
  underscore exception
- Tailwind CSS config scoped to src/client, PostCSS with autoprefixer
- Playwright config: Chromium-only E2E against dev server
- bin/session-viewer.js: CLI entry point that re-execs via tsx with
  browser-open flag

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

package.json

@@ -0,0 +1,54 @@
+{
+  "name": "session-viewer",
+  "version": "1.0.0",
+  "description": "Browse, filter, redact, and export Claude Code sessions as self-contained HTML",
+  "type": "module",
+  "bin": {
+    "session-viewer": "./bin/session-viewer.js"
+  },
+  "scripts": {
+    "dev": "concurrently \"npm run dev:server\" \"npm run dev:client\"",
+    "dev:server": "tsx watch src/server/index.ts",
+    "dev:client": "vite",
+    "build": "tsc && vite build",
+    "preview": "vite preview",
+    "test": "vitest run",
+    "test:watch": "vitest",
+    "test:e2e": "playwright test",
+    "typecheck": "tsc --noEmit",
+    "lint": "eslint . --ext .ts,.tsx"
+  },
+  "dependencies": {
+    "express": "^4.21.0",
+    "highlight.js": "^11.10.0",
+    "marked": "^14.0.0",
+    "marked-highlight": "^2.2.3",
+    "open": "^10.1.0",
+    "react": "^18.3.1",
+    "react-dom": "^18.3.1"
+  },
+  "devDependencies": {
+    "@eslint/js": "^9.0.0",
+    "@playwright/test": "^1.48.0",
+    "@testing-library/jest-dom": "^6.9.1",
+    "@testing-library/react": "^16.3.2",
+    "@types/express": "^4.17.21",
+    "@types/node": "^22.0.0",
+    "@types/react": "^18.3.0",
+    "@types/react-dom": "^18.3.0",
+    "@types/supertest": "^6.0.0",
+    "@vitejs/plugin-react": "^4.3.0",
+    "autoprefixer": "^10.4.20",
+    "concurrently": "^9.0.0",
+    "eslint": "^9.0.0",
+    "jsdom": "^27.4.0",
+    "postcss": "^8.4.47",
+    "supertest": "^7.0.0",
+    "tailwindcss": "^3.4.13",
+    "tsx": "^4.19.0",
+    "typescript": "^5.6.0",
+    "typescript-eslint": "^8.0.0",
+    "vite": "^5.4.0",
+    "vitest": "^2.1.0"
+  }
+}