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 formatting and shared recorder-core capture/error utilities.

• Adds offer, answer, and missing-description tests for WebRTC signaling conversion.
• Adds recording-mode detection and display-capture error classification tests.

Confidence Score: 4/5

The PR appears safe to merge, with one non-blocking test-accuracy issue where undefined input is named but not exercised.

The production code is unchanged and the new tests resolve against source correctly; only the WebRTC missing-description test overstates the edge cases it verifies.

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 focused session-description conversion coverage, but one test claims undefined-input coverage without exercising undefined.
packages/recorder-core/tests/recorder-utils.test.ts	Adds valid coverage for recording-mode heuristics, cancellation classification, and retryable display-media errors.

Prompt To Fix All With AI

### Issue 1
apps/chrome-extension/src/shared/webrtc.test.ts:83
**Undefined case is not tested**

This test claims coverage for both `null` and `undefined`, but its only assertion passes `null`. An independent regression in undefined-input handling would therefore remain undetected while the test name implies that case is covered.

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

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Greptile also left 1 inline comment on this PR.

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[greptile-apps]

Undefined case is not tested

This test claims coverage for both null and undefined, but its only assertion passes null. An independent regression in undefined-input handling would therefore remain undetected while the test name implies that case is covered.

Prompt To Fix With AI

This is a comment left during a code review.
Path: apps/chrome-extension/src/shared/webrtc.test.ts
Line: 83

Comment:
**Undefined case is not tested**

This test claims coverage for both `null` and `undefined`, but its only assertion passes `null`. An independent regression in undefined-input handling would therefore remain undetected while the test name implies that case is covered.

---

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