feat(01-01): monorepo scaffold with root configs and shared package

- Root package.json with pnpm workspace, Turborepo, Biome, TypeScript
- pnpm-workspace.yaml defining apps/* and packages/* workspaces
- turbo.json with build, dev, lint, type-check task definitions
- tsconfig.base.json with strict mode and bundler module resolution
- biome.json with formatter and linter configuration
- .gitignore, .env.example, .dockerignore
- @tessera/shared package with APP_NAME constant and HealthResponse type
- pnpm-lock.yaml generated from successful install

package.json

@@ -0,0 +1,16 @@
+{
+  "name": "tessera",
+  "private": true,
+  "packageManager": "pnpm@9.15.0",
+  "scripts": {
+    "dev": "turbo dev",
+    "build": "turbo build",
+    "lint": "turbo lint",
+    "type-check": "turbo type-check"
+  },
+  "devDependencies": {
+    "turbo": "^2.9.18",
+    "@biomejs/biome": "^2.5.0",
+    "typescript": "^5.5.0"
+  }
+}