feat: complete working-copies workspace-first cleanup

- Remove clone_mode/branch/new_branch from frontend create session flow.
- Add workspace picker to CreateSessionForm; auto-create default workspace when repo selected.
- Fix tool-starter.tsx and use-start-tool.ts createInstance signatures after API change.
- Remove clone mode badge from SessionCard.
- Delete stale backend unit tests referencing removed clone_mode schema fields.
- Update OpenSpec working-copies tasks and mark change completed.
- Regenerate project maps.

Quality gates: npm run typecheck, npm run lint, npm test -- --run (82 passed),
python3 -m py_compile on changed backend files.

apps/web/src/hooks/use-start-tool.ts

@@ -35,12 +35,9 @@ export function useStartTool(): UseStartToolResult {
 					workspace.repo_id,
 					toolTypeId,
 					displayName || workspace.name,
-					undefined,
-					undefined,
-					undefined,
+					workspace.id,
 					configProfileId,
 					[],
-					workspace.id,
 				);
 				await startInstance(
 					workspace.project_id,