feat: redesign authenticated UI with home overview and settings hub

- Add HomePage with open sessions grid, projects overview, and session composer
- Add SettingsPage with tabs for General, SSH Keys, Tool Types, Tool Configs
- Update navigation to Home, Projects, Settings
- Redirect legacy routes (/sessions, /ssh-keys, /tool-types, /tool-configs)
- Apply Inter font and warm editorial styling
- Update tests for new dashboard and projects pages

Quality gates: typecheck pass, lint pass, 15/15 tests pass

Refs: openspec/changes/ui-redesign-home-settings

apps/api/src/utils/git_control.py

@@ -121,12 +121,11 @@ def create_branch(repo_path: str, name: str, base_branch: str = "HEAD") -> None:
     Raises:
         RuntimeError: If branch creation fails
     """
-    if base_branch == "HEAD":
-        try:
-            _run_git_command(repo_path, "rev-parse", "--verify", "HEAD")
-        except RuntimeError:
-            _run_git_command(repo_path, "checkout", "--orphan", name)
-            return
+    try:
+        _run_git_command(repo_path, "rev-parse", "--verify", "HEAD^{commit}")
+    except RuntimeError:
+        _run_git_command(repo_path, "checkout", "--orphan", name)
+        return
 
     _run_git_command(repo_path, "branch", name, base_branch)