[codex] fix dashboard stale lazy chunk reload

[anarkh]

Summary

Fix dashboard route failures after the CLI/dashboard assets are rebuilt while an existing App or browser window still holds the previous SPA entry script.

Root Cause

Dashboard route pages are lazy-loaded as content-hashed chunks. If an already-loaded app.js points to an old chunk name that has been removed by a rebuild or upgrade, routes such as groups, roles, and bot defaults fail with Failed to fetch dynamically imported module.

Changes

• Add a focused stale lazy-chunk detector for dashboard route imports.
• Reload the dashboard shell once per missing chunk using a sessionStorage guard.
• Preserve the original route error path for ordinary render failures or when browser storage cannot be read.
• Add unit coverage for one-time reload behavior, ordinary errors, storage failures, and browser storage getter failures.

Validation

• pnpm exec vitest run --project unit test/dashboard-stale-chunk-reload.test.ts test/dashboard-route-lifecycle.test.ts test/dashboard-route-smoke.test.ts
• pnpm exec tsc --noEmit
• git diff --check