fix: strip remote prefix from branch names in list_branches

Git branch -a --format=%(refname:short) returns remote branches as
'origin/branch-name', not 'remotes/origin/branch-name'. The code was
only filtering 'remotes/' prefix, causing clone to fail with branch
names like 'origin/feat/foo'.

Now properly detects remote names using 'git remote' and strips the
remote prefix (e.g., 'origin/') from branch names.

apps/api/src/utils/git_files.py

@@ -289,19 +289,37 @@ def list_branches(repo_path: str) -> tuple[list[BranchInfo], str]:
     branches: list[BranchInfo] = []
     default_branch = "main"
 
+    # Get list of remote names to properly filter remote tracking branches
+    try:
+        remote_output = _run_git_command(repo_path, "remote")
+        remote_names = {r.strip() for r in remote_output.strip().split("\n") if r.strip()}
+    except RuntimeError:
+        remote_names = set()
+
     for line in output.strip().split("\n"):
         if not line:
             continue
 
         branch_name = line.strip()
-        # Skip remote tracking branches (they start with remotes/)
-        if branch_name.startswith("remotes/"):
-            # Extract just the branch name part
-            parts = branch_name.split("/", 2)
-            if len(parts) >= 3:
-                branch_name = parts[2]
-            else:
-                continue
+        
+        # Skip detached HEAD pointer
+        if branch_name == "HEAD":
+            continue
+            
+        # Skip remote tracking branches - they appear as "origin/branch-name"
+        # Check if first part is a remote name
+        if "/" in branch_name:
+            first_part = branch_name.split("/", 1)[0]
+            if first_part in remote_names:
+                # Extract just the branch name part (after "origin/")
+                branch_name = branch_name.split("/", 1)[1]
+            elif branch_name.startswith("remotes/"):
+                # Handle "remotes/origin/branch-name" format
+                parts = branch_name.split("/", 2)
+                if len(parts) >= 3:
+                    branch_name = parts[2]
+                else:
+                    continue
 
         # Skip duplicates
         if any(b.name == branch_name for b in branches):