WIP: frontend clone_mode removal in create form and API

- Remove clone_mode/branch/new_branch from createInstance API helper
- Remove clone mode UI and branch fields from CreateSessionForm

Remaining: wire workspace_id in form/tool-starter, remove session-card badge, tests

.gitignore

@@ -17,6 +17,7 @@ __pycache__/
 *.so
 .python-version
 .venv/
+.venv-test/
 venv/
 env/
 .pytest_cache/
@@ -56,3 +57,4 @@ Thumbs.db
 .pi-lens/
 minerv3/
 .cache/
+openspec-audit-report.md