feat(FN-2477): add executable OpenClaw runtime adapter

- Replace deferred OpenClaw placeholder runtime with an executable adapter that creates sessions, prompts with fallback, describes models, and disposes safely
- Add a dedicated pi-module seam and local runtime contract types to decouple plugin compilation from engine internals while preserving runtime behavior
- Update OpenClaw plugin metadata, manifest/package descriptions, and README to reflect active execution support instead of deferred status
- Harden dashboard DevServerStore save flow against ENOENT temp-directory races and add regression coverage for project-directory removal during save

plugins/fusion-plugin-openclaw-runtime/manifest.json

@@ -2,13 +2,13 @@
   "id": "fusion-plugin-openclaw-runtime",
   "name": "OpenClaw Runtime Plugin",
   "version": "0.1.0",
-  "description": "OpenClaw runtime plugin for Fusion with experimental deferred execution",
+  "description": "Provides OpenClaw runtime for Fusion AI agents",
   "author": "Fusion Team",
   "homepage": "https://github.com/gsxdsm/fusion",
   "runtime": {
     "runtimeId": "openclaw",
     "name": "OpenClaw Runtime",
-    "description": "Experimental OpenClaw runtime integration for Fusion tasks (execution deferred)",
+    "description": "OpenClaw-backed AI session using the user's configured pi provider and model",
     "version": "0.1.0"
   }
 }