[Tests] Cover the Cloudflare tunnel timeout with no reported error

[github-actions]

WHY are these changes introduced?

The seven-day review of Main tests (2026-09-25 to 2026-10-02 UTC) found ten failed runs. Every evidenced flake in that window is already claimed, so this PR closes a coverage gap instead:

• Version-command subprocess timeouts, seven runs across Windows and macOS on Node 22/24 (Node 22.12.0 in windows-latest, Node 24.1.0 in windows-latest, Node 22.12.0 in macos-latest) — addressed by open PR Stabilize version, profile, and package cache tests #8669.
• checkForCachedNewVersion returning undefined from a shared on-disk cache, one run (Node 24.1.0 in windows-latest) — the same describe block is rewritten by Stabilize version, profile, and package cache tests #8669.
• runWithRateLimit clock boundary, one run (Node 26.1.0 in ubuntu-latest) — fixed by merged PR [Tests] Fix flaky outdated rate-limit cache test #8705.

The remaining failures in the window were cancellations rather than test failures.

The Cloudflare tunnel timeout handler has two branches: report the last collected cloudflared errors, or fall back to Could not start Cloudflare tunnel: unknown error. when none were collected. Only the first branch was exercised. I confirmed the gap by changing the fallback message in tunnel.ts and running the package suite — all 19 tests still passed, so that user-facing message could change or break silently.

WHAT is this pull request doing?

Adds one test to packages/plugin-cloudflare/src/tunnel.test.ts that writes a cloudflared log line matching neither the URL, connection, nor known-error patterns, then advances the fake clock past the unit-test tunnel timeout and asserts the fallback status.

No production code changes. The test follows the fake-timer pattern of the neighbouring cleans errors coming from the log case, including its try/finally restore, and asserts the public getTunnelStatus() contract rather than internal wiring.

The test is load-bearing: with the fallback message mutated it fails and no other test does; restored, it passes.

Validation on Linux / Node 26.1.0: the file and the full plugin-cloudflare suite pass (19 tests), five consecutive --sequence.shuffle runs pass, and --pool=forks and --no-file-parallelism pass. lint and type-check are clean. The branch under test is platform-independent and uses fake timers, so it carries no OS-specific timing risk; Windows and macOS confirmation comes from CI.

How to manually test your changes?

CI

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes
• I've considered analytics changes to measure impact
• The change is user-facing — I've identified the correct bump type (patch for bug fixes · minor for new features · major for breaking changes) and added a changeset with pnpm changeset add