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

.gitignore

@@ -0,0 +1,24 @@
+# Dependencies
+node_modules/
+
+# Build outputs
+.next/
+dist/
+
+# Turborepo
+.turbo/
+
+# Environment variables
+.env
+
+# Logs
+*.log
+
+# macOS
+.DS_Store
+
+# Test coverage
+coverage/
+
+# pnpm store
+.pnpm-store/