feat: add OpenCode CLI path override and settings UI

- Add opencodeBinary field to settings and persistence flow
- Introduce OpenCode CLI settings panel with Browse and Save actions

packages/vscode/package.json

@@ -196,6 +196,11 @@
           "type": "string",
           "default": "",
           "description": "URL of an external OpenCode API server. Leave empty to auto-start a local instance."
+        },
+        "openchamber.opencodeBinary": {
+          "type": "string",
+          "default": "",
+          "description": "Optional absolute path to the opencode CLI binary. Useful if PATH lookup fails. Requires window reload or API restart to apply."
         }
       }
     }
@@ -224,7 +229,7 @@
   },
   "dependencies": {
     "@openchamber/ui": "workspace:*",
-    "@opencode-ai/sdk": "^1.1.48",
+    "@opencode-ai/sdk": "^1.1.52",
     "adm-zip": "^0.5.16",
     "jsonc-parser": "^3.3.1",
     "react": "^19.1.1",