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

apps/api/src/schemas/tool/__init__.py

@@ -1,6 +1,10 @@
 """Tool schemas module."""
 
-from src.schemas.tool.tool_instance import CreateInstanceRequest, StartInstanceRequest
+from src.schemas.tool.tool_instance import (
+    CreateInstanceRequest,
+    CreateWorkspaceInstanceRequest,
+    StartInstanceRequest,
+)
 from src.schemas.tool.tool_type import (
     ToolTypeCreate,
     ToolTypeResponse,
@@ -10,6 +14,7 @@ from src.schemas.tool.tool_type import (
 
 __all__ = [
     "CreateInstanceRequest",
+    "CreateWorkspaceInstanceRequest",
     "StartInstanceRequest",
     "ToolTypeCreate",
     "ToolTypeResponse",