fix(web): Restart failures surface, no step timeout on deployed packages, roster Chat link navigates (CL-8521)

[TheGreatAxios]

Summary

• Restart useMutations in agents-page.tsx and chat-thread-page.tsx (two call sites) now have onError: report through reportError, toast stage copy when the cause is a WorkbenchCreateError, generic copy otherwise (describeRestartFailure in workbench-create.ts, mirroring describeWorkbenchCreateFailure).
• buildAgentDefinitionJson no longer emits timeout: 120000 on the deployed step — a step timeout stays armed across an approval park and would abort a run waiting on a person to answer an ask-gated tool call, same reasoning Myra's own definition already documents.
• Fixed the roster "Chat" link not navigating: the first-run tour (FirstRunTour, mounted globally in AppShell) renders a full-page Joyride overlay that, by default, swallows clicks anywhere outside the current spotlight target. On /agents, the tour's step 1 spotlight only exposes the sidebar, so a click on the Chat link landed on the overlay instead of the anchor. Added spotlightClicks to the Joyride props so the overlay's backdrop lets clicks pass through to the page underneath while still showing the tour visually.

Verification

• Reproduced item 3 with agent-browser against the running dev server: clicking the Chat link failed with "Element is covered by <div.react-joyride__overlay>" before the fix.
• bunx tsc -p apps/web --noEmit, bun run lint, bun run fmt, apps/web bun run build, apps/web bun test ./src all pass.

[linear-code]

CL-8521