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

turbo.json

@@ -0,0 +1,21 @@
+{
+  "$schema": "https://turborepo.dev/schema.json",
+  "tasks": {
+    "build": {
+      "dependsOn": ["^build"],
+      "outputs": ["dist/**", ".next/**"],
+      "inputs": ["src/**", "package.json", "tsconfig.json"]
+    },
+    "dev": {
+      "cache": false,
+      "persistent": true
+    },
+    "lint": {
+      "outputs": []
+    },
+    "type-check": {
+      "dependsOn": ["^build"],
+      "outputs": []
+    }
+  }
+}