fix(web): shell polish for failed-run insight, palette, tour, and settings (CL-8459)

[TheGreatAxios]

Summary

• A failed run's detail page now shows its failure message and a link to its full event log, read from the stock GET /workflows/runs/:runId/events route.
• The command palette no longer offers "Go to insights"; Insights stays reachable from Settings.
• The first-run tour's composer step targeted an anchor not guaranteed to be mounted on the landing page (console warned "Target not mounted"); the step is dropped.
• Settings → General's "Agent" section (a display-only, unauthored timezone readout) is removed — it carried no actionable content.
• The Tools page notes packages are read-only there, since no per-package versions view exists yet.
• The Skills detail page's existing behavior was reviewed: it already reads/writes SKILL.md content over the asset's git remote, so there was no stale "not readable yet" disclosure to keep or remove.

Changes

• apps/web/src/insights-api.ts: arktype schema for the run-events response, a path helper, and runFailureMessage reading RunFailed/StepFailed event bodies.
• apps/web/src/pages/insights-page.tsx: InsightsRunDetail fetches and renders the failure message plus a togglable event list for a failed run, via useQuery-backed useAPIQuery.
• apps/web/src/command-palette-actions.ts (+ test): removed the go-insights action command.
• apps/web/src/shell/first-run-tour.tsx: dropped the composer step.
• apps/web/src/settings/{account-section,index,strings}.ts: removed AgentGeneralSection.
• apps/web/src/pages/tools-page.tsx: added the read-only note above the packages table.

Testing

• bun run typecheck
• Targeted: bun test ./src/command-palette-actions.test.ts ./src/pages/insights-page.test.ts ./src/pages/insights-page-render.test.tsx ./src/settings
• bun run check (full monorepo typecheck/lint/fmt/test)
• Live verification against the local dev stack was attempted via agent-browser; the app sits behind a sign-in wall with no available local credentials, so pages beyond the login screen could not be exercised this session.

[linear-code]

CL-8459