fix: make the new-chain test guard fail CI instead of exiting 0

[kuzdogan]

Summary

The "there needs to be at least one passing test" guard for new chains lived in a suite-level after() hook in tests/chain-tests.test.ts. When it throws, Node reports the suite as failed but leaves the failure count at 0 — and Node >= 22.22 (CI runs node-version: "22") derives the process exit code from those counters. So the runner exited 0 and the test-new-chain job went green on a run where the guard had actually fired.

Seen on #117, run 30430598954:

✖ Test Supported Chains (466.288187ms)
ℹ tests 2 / pass 1 / fail 0
✖ failing tests:
  Error: There needs to be at least one passing test. Did you forget to add a test for your new chain with the id(s) 641230?

…and the step still succeeded.

Reproduced with a minimal test (one passing it, one throwing suite-level after):

Node	exit code
20.12.2	1
22.5.1	1
22.22.0	0
23.5.0	0

A failing before() hook or a genuinely failing it() still exits 1, so this is specific to after. Neither downstream safety net catches it: the junit XML has no failing <testcase> (a hook failure isn't one), and mikepenz/action-junit-report runs with fail_on_failure: false.

Change

Move the guard out of the hook into a real test registered after the per-chain loop, so anyTestsPass is already settled when it runs. It now exits non-zero and appears as a failing testcase in the junit report / PR annotations.

🤖 Generated with Claude Code