feat: warn when Honcho token is missing

[utpalsinghdev]

Summary

I pointed OpenConcho at a Honcho instance and left the token blank. The app loaded in a half-working state: workspaces showed up, conclusions failed, and nothing said the token was missing.

The health check already maps 401/403 to auth-required. That only showed as a small sidebar dot (hover tooltip, hidden on a narrow sidebar). This PR adds a layout banner for the missing-token case: the instance requires a token, none is configured, and Settings is one click away. Public self-hosted instances with no auth still get no warning. The existing health dot is unchanged.

Type

• New feature

Test plan

• pnpm lint passes
• pnpm test passes
• @openconcho/web build succeeds (tsc -b && vite build)
• Tested in browser against a local mock Honcho:
  • 401 with an empty token showed the banner on the dashboard
  • "Add token in Settings" opened /settings and the instance list
  • Saving a fake token (test-token) cleared the banner. The token never appeared in page text.
  • A public instance that returned 200 with an empty token showed no banner
  • At 375px width the banner stayed visible without hovering

Related issues

Closes #102

Related to #95, which is about authenticating access to the OpenConcho Web UI. This PR is about the token OpenConcho sends to Honcho.