feat: add multi-model cleanup tool and CLI command

- Bump `@opencode-ai/plugin` dependency from 1.2.27 to 1.3.0.
- Introduce `cleanup` command in CLI with force and remote options.
- Export `cleanupMultiModel` from core index.
- Register `multi-model-cleanup` tool in plugin and update exports.
- Add `CleanupOptions` and `CleanupResult` types to define cleanup behavior and results.

.opencode/package.json

@@ -6,10 +6,10 @@
     "test": "bun test"
   },
   "dependencies": {
-    "@opencode-ai/plugin": "1.2.27"
+    "@opencode-ai/plugin": "1.3.0"
   },
   "devDependencies": {
     "@types/bun": "^1.3.10",
     "@types/node": "^25.5.0"
   }
-}
+}