test(chrome-extension): verify WebRTC session description formatting

[gcoinstash-cmd]

Summary of Changes

• Adds unit test coverage for WebRTC session description exchange in Chrome extension recording pipeline.
• Test suite passed 100% green.

Greptile Summary

This PR expands unit coverage for Chrome-extension WebRTC session-description conversion and shared recorder-core capture/error utilities.

• Tests offer and answer SDP conversion plus missing-description handling.
• Tests recording-mode label heuristics, cancellation classification, and display-media fallback classification.

Confidence Score: 4/5

The PR appears safe to merge, with one non-blocking test-coverage mismatch to correct.

The recorder-core tests align with the implementation and runtime, while the WebRTC test only needs an explicit undefined assertion to match its stated coverage.

Files Needing Attention: apps/chrome-extension/src/shared/webrtc.test.ts

Important Files Changed

Filename	Overview
apps/chrome-extension/src/shared/webrtc.test.ts	Adds valid conversion assertions, but the missing-description test claims undefined coverage without exercising undefined.
packages/recorder-core/tests/recorder-utils.test.ts	Adds assertions consistent with the recording-mode and error-classification utility contracts and configured test runtime.

Prompt To Fix All With AI

### Issue 1
apps/chrome-extension/src/shared/webrtc.test.ts:81-86
**Undefined case remains untested**

This test claims coverage for both `null` and `undefined`, but invokes the helper only with `null`. A regression that handles these inputs differently would therefore leave the suite green despite the test description.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (1): Last reviewed commit: "test(chrome-extension): verify WebRTC se..." | Re-trigger Greptile}

Greptile also left 1 inline comment on this PR.

[superagent-security]

Manage your Superagent protection

Superagent has paused scans for this repository because this unlinked GitHub App installation has used all three included PR scans.

You have 0 of 3 included PR scans remaining.

Create a free account to continue protection, manage scan settings, review security history, and control which repositories are protected.

[greptile-apps]

Undefined case remains untested

This test claims coverage for both null and undefined, but invokes the helper only with null. A regression that handles these inputs differently would therefore leave the suite green despite the test description.

Prompt To Fix With AI

This is a comment left during a code review.
Path: apps/chrome-extension/src/shared/webrtc.test.ts
Line: 81-86

Comment:
**Undefined case remains untested**

This test claims coverage for both `null` and `undefined`, but invokes the helper only with `null`. A regression that handles these inputs differently would therefore leave the suite green despite the test description.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.