fix(orb): drop check_run from relay forward set

[JSONbored]

Summary

check_run events are fired once per CI job per repo — at the scale of a
busy monorepo that's thousands of events per day. Forwarding them to
brokered self-host containers creates a CI firehose: the container receives
events it can't meaningfully act on and burns queue capacity.

check_suite is sufficient: it fires once per push/PR sync, and the
re-review trigger in processors.ts (eventName !== "check_run" && eventName !== "check_suite") handles both. Dropping check_run from
RELAY_FORWARD_EVENTS is therefore lossless for all brokered containers.

A regression assertion added to the existing skip-test pins check_run as
intentionally excluded with an explanatory comment so no future refactor
accidentally re-adds it.

Scope

• New public API or changed API signature
• DB schema / migration
• Self-host / Orb / broker path
• Auth / session / CORS path
• UI change
• Docs change

Validation

• npx vitest run test/integration/orb-relay.test.ts — 19 tests, all pass
• npm run test:ci — 258 test files passed, 0 failed

Safety

• No secrets, tokens, wallets, hotkeys, trust scores, or reward values introduced
• No auth/CORS changes
• No UI changes
• Change is backward-compatible: brokered containers simply stop receiving the CI firehose; no new required config

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.35%. Comparing base (f160cbb) to head (c3c65f8).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1383   +/-   ##
=======================================
  Coverage   95.35%   95.35%           
=======================================
  Files         191      191           
  Lines       20711    20711           
  Branches     7488     7488           
=======================================
  Hits        19750    19750           
  Misses        380      380           
  Partials      581      581           

Files with missing lines	Coverage Δ
src/orb/relay.ts	100.00% <ø> (ø)

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