fix(opencode): skip reading live config when editing provider

OpenCode's read_live_settings returns the full opencode.json file
instead of just the provider fragment. This caused the edit dialog
to save the complete config structure as settingsConfig, creating
nested provider configurations.

For OpenCode's additive mode, use DB config directly since each
provider's config is stored independently.

src/components/providers/EditProviderDialog.tsx

@@ -62,6 +62,17 @@ export function EditProviderDialog({
         return;
       }
 
+      // OpenCode uses additive mode - each provider's config is stored independently in DB
+      // Reading live config would return the full opencode.json (with $schema, provider, mcp etc.)
+      // instead of just the provider fragment, causing incorrect nested structure on save
+      if (appId === "opencode") {
+        if (!cancelled) {
+          setLiveSettings(null);
+          setHasLoadedLive(true);
+        }
+        return;
+      }
+
       try {
         const currentId = await providersApi.getCurrent(appId);
         if (currentId && provider.id === currentId) {