Fix: wrap provider resolution in Effect pipeline so fallback to 'main' is reachable

The inner `yield* sourceControlProvider(cwd)` could fail before
`.getDefaultBranch()` was called, bypassing the Effect.catch handler
and preventing the graceful fallback to "main". By piping the provider
resolution through Effect.flatMap and wrapping the entire chain with
Effect.catch, both provider-resolution failures and getDefaultBranch
failures now correctly fall through to the "main" default.

Author: cursoragent

apps/server/src/git/GitManager.ts

@@ -1045,9 +1045,10 @@ export const makeGitManager = Effect.fn("makeGitManager")(function* () {
       }
     }
 
-    const defaultFromProvider = yield* (yield* sourceControlProvider(cwd))
-      .getDefaultBranch({ cwd })
-      .pipe(Effect.catch(() => Effect.succeed(null)));
+    const defaultFromProvider = yield* sourceControlProvider(cwd).pipe(
+      Effect.flatMap((provider) => provider.getDefaultBranch({ cwd })),
+      Effect.catch(() => Effect.succeed(null)),
+    );
     if (defaultFromProvider) {
       return defaultFromProvider;
     }