fix: handle unborn HEAD branch creation

- Create orphan branches when HEAD does not exist yet\n- Use current branch as the default branch base in the toolbar\n- Keep push disabled for remote-less repos\n\nQuality gates: vitest repositories-settings-tab (passed); api pytest blocked by missing fastapi in environment

apps/web/src/components/git-toolbar.tsx

@@ -112,7 +112,7 @@ export const GitToolbar = ({
     if (!newBranchName.trim()) return;
     setLoading(true);
     try {
-      await createBranch(projectId, repoId, newBranchName, newBranchBase || "HEAD");
+      await createBranch(projectId, repoId, newBranchName, newBranchBase || currentBranch || "HEAD");
       setShowNewBranch(false);
       setNewBranchName("");
       setNewBranchBase("");
@@ -131,6 +131,8 @@ export const GitToolbar = ({
     status.untracked.length > 0
   );
 
+  const canSync = hasRemote;
+
   return (
     <div className="git-toolbar">
       {error && <div className="toolbar-error">{error}</div>}
@@ -169,7 +171,7 @@ export const GitToolbar = ({
           <button
             className="toolbar-button"
             onClick={handleFetch}
-            disabled={loading || !hasRemote}
+            disabled={loading || !canSync}
             type="button"
           >
             <Icon name="fetch" size="sm" /> Fetch
@@ -177,7 +179,7 @@ export const GitToolbar = ({
           <button
             className="toolbar-button"
             onClick={handlePull}
-            disabled={loading || !hasRemote}
+            disabled={loading || !canSync}
             type="button"
           >
             <Icon name="pull" size="sm" /> Pull
@@ -186,7 +188,7 @@ export const GitToolbar = ({
           <button
             className="toolbar-button"
             onClick={handlePush}
-            disabled={loading || !status?.ahead}
+            disabled={loading || !canSync || !status?.ahead}
             type="button"
           >
             <Icon name="push" size="sm" /> Push