chore: fix all biome lint errors

- Auto-fix string concatenation → template literals
- Remove unused imports
- Prefix unused function with underscore
- Format fixes across multiple files

packages/workflow-gateway/package.json

@@ -1,7 +1,10 @@
 {
   "name": "@uncaged/workflow-gateway",
   "version": "0.3.16",
-  "files": ["dist", "package.json"],
+  "files": [
+    "dist",
+    "package.json"
+  ],
   "type": "module",
   "exports": {
     ".": "./src/index.ts",
@@ -18,4 +21,4 @@
     "@cloudflare/workers-types": "^4.20260425.1",
     "wrangler": "^4.20.0"
   }
-}
+}