feat: support remote_sync for plugin install/uninstall. (#14878)

- Added forceRemoteSync to plugin/install and plugin/uninstall.
- With forceRemoteSync=true, we update the remote plugin status first,
then apply the local change only if the backend call succeeds.
- Kept plugin/list(forceRemoteSync=true) as the main recon path, and for
now it treats remote enabled=false as uninstall. We
will eventually migrate to plugin/installed for more precise state
handling.

codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json

@@ -5968,6 +5968,10 @@
     "PluginInstallParams": {
       "$schema": "http://json-schema.org/draft-07/schema#",
       "properties": {
+        "forceRemoteSync": {
+          "description": "When true, apply the remote plugin change before the local install flow.",
+          "type": "boolean"
+        },
         "marketplacePath": {
           "$ref": "#/definitions/AbsolutePathBuf"
         },
@@ -6288,6 +6292,10 @@
     "PluginUninstallParams": {
       "$schema": "http://json-schema.org/draft-07/schema#",
       "properties": {
+        "forceRemoteSync": {
+          "description": "When true, apply the remote plugin change before the local uninstall flow.",
+          "type": "boolean"
+        },
         "pluginId": {
           "type": "string"
         }