refactor: cursor-agent uses runtime.extract for workspace detection

- Remove llmProvider and workspace from CursorAgentConfig (now just command/model/timeout)
- extractWorkspacePath uses runtime.extract + runtime.cas instead of standalone reactor
- TextProducerFn signature gains runtime parameter: (ctx, prompt, runtime)
- develop-entry.ts hardcodes cursor-agent path, no more env var dependency
- Drop @uncaged/workflow-reactor dep from workflow-agent-cursor
- Update tests for simplified config

小橘 <xiaoju@shazhou.work>

.changeset/config.json

@@ -2,16 +2,10 @@
   "$schema": "https://unpkg.com/@changesets/config@3.1.4/schema.json",
   "changelog": "@changesets/cli/changelog",
   "commit": false,
-  "fixed": [
-    [
-      "@uncaged/*"
-    ]
-  ],
+  "fixed": [["@uncaged/*"]],
   "linked": [],
   "access": "public",
   "baseBranch": "main",
   "updateInternalDependencies": "patch",
-  "ignore": [
-    "@uncaged/workflow-dashboard"
-  ]
+  "ignore": ["@uncaged/workflow-dashboard"]
 }