fix: allow workspace creation from workspaces page

- Replace awkward first-workspace-guessing logic with inline project/repo selector
- New WorkspaceCreateInline component with cascading dropdowns:
  - Select project → loads repositories for that project
  - Select repository → enter workspace name + branch
  - Submit creates workspace via top-level POST /workspaces/
- Add createWorkspaceTopLevel() API client for flat endpoint
- Works even with zero existing workspaces (shows create button in empty state)
- Add CSS grid layout for inline create form
- TypeScript + eslint clean

apps/web/src/router.tsx

@@ -58,7 +58,10 @@ export const AppRouter = () => {
 				</Route>
 				<Route path="sessions" element={<SessionsPage />} />
 				<Route path="workspaces" element={<WorkspacesPage />} />
-				<Route path="workspaces/:workspaceId" element={<WorkspaceDetailPage />} />
+				<Route
+					path="workspaces/:workspaceId"
+					element={<WorkspaceDetailPage />}
+				/>
 				<Route path="tool-workshop" element={<ToolWorkshopPage />} />
 				<Route
 					path="instances/:instanceId/terminal"