feat(broker): scaffold apps/broker workspace (bun WS runtime, no port yet)

- @claudemesh/broker package with bun dev/start scripts
- src/index.ts stub: WS server on BROKER_PORT, SIGTERM cleanup
- src/env.ts: Zod-validated env (BROKER_PORT, DATABASE_URL, STATUS_TTL_SECONDS, HOOK_FRESH_WINDOW_SECONDS)
- src/db.ts: re-exports Drizzle client from @turbostarter/db
- src/broker.ts + src/types.ts: placeholders for step 8 port
- README documents run commands, env vars, deploy targets
- tsconfig extends @turbostarter/tsconfig base
- eslint.config.js extends @turbostarter/eslint-config/base

Dependencies declared but not installed yet (ws, drizzle-orm, zod,
libsodium-wrappers + workspace deps). turbo.json unchanged: the global
dev task already has persistent=true + cache=false which is what the
broker needs.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/broker/package.json

@@ -0,0 +1,33 @@
+{
+  "name": "@claudemesh/broker",
+  "version": "0.1.0",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "clean": "git clean -xdf .cache .turbo dist node_modules",
+    "dev": "bun --hot src/index.ts",
+    "start": "bun src/index.ts",
+    "format": "prettier --check . --ignore-path ../../.gitignore",
+    "lint": "eslint",
+    "typecheck": "tsc --noEmit"
+  },
+  "prettier": "@turbostarter/prettier-config",
+  "dependencies": {
+    "@turbostarter/db": "workspace:*",
+    "@turbostarter/shared": "workspace:*",
+    "drizzle-orm": "catalog:",
+    "libsodium-wrappers": "0.7.15",
+    "ws": "8.19.1",
+    "zod": "catalog:"
+  },
+  "devDependencies": {
+    "@turbostarter/eslint-config": "workspace:*",
+    "@turbostarter/prettier-config": "workspace:*",
+    "@turbostarter/tsconfig": "workspace:*",
+    "@types/libsodium-wrappers": "0.7.14",
+    "@types/ws": "8.5.13",
+    "eslint": "catalog:",
+    "prettier": "catalog:",
+    "typescript": "catalog:"
+  }
+}