Treat Chrome's "network error" as a lost connection - #1434

Summary

Chrome raises TypeError: network error when the connection drops while a response body is being read. isNetworkError did not know this wording, so a user on Cloud got the generic "Something went wrong" screen instead of the "Connection lost" page that reloads by itself once the network is back (Sentry ANYTHINGMCP-CLOUD-FRONTEND-G).

Cloud and self-hosted behave the same: this is the shared frontend error boundary.

Changes

• packages/frontend/src/lib/network-error.ts: add /^network error$/i to the recognised messages (exact match, so longer messages that merely contain the words are not caught).
• packages/frontend/tests/e2e/network-drop.spec.ts: one more assertion in the isNetworkError test.

Type

• Bug fix

Testing

• Added/updated unit tests
• Regex checked with node: matches network error and Network Error, not network error x.
• Frontend Playwright runs in CI (playwright.yml).

Checklist

• My code follows the existing code style
• I have tested my changes locally
• I have updated documentation (if applicable): not needed
• This PR has a descriptive title

Related Issues

Sentry ANYTHINGMCP-CLOUD-FRONTEND-G