Fix e2e helpers: workspace IDs are strings, not numbers

After removing SQLite, workspace IDs are cwd path strings instead of
numeric database IDs. Update type declarations in workspace-setup.ts
and terminal-perf.ts, and remove the numeric parsing in
fetchWorkspaceById that would reject path-based IDs.

packages/app/e2e/helpers/terminal-perf.ts

@@ -9,7 +9,7 @@ export type TerminalPerfDaemonClient = {
   connect(): Promise<void>;
   close(): Promise<void>;
   openProject(cwd: string): Promise<{
-    workspace: { id: number; name: string; projectRootPath: string } | null;
+    workspace: { id: string; name: string; projectRootPath: string } | null;
     error: string | null;
   }>;
   createTerminal(