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

The PR expands unit coverage around WebRTC session-description conversion and several shared recorder utilities.

• Adds offer, answer, and missing-description conversion tests for the Chrome extension.
• Adds recording-mode label heuristic tests.
• Adds cancellation and display-media retry error classification tests.

Confidence Score: 4/5

The PR appears safe to merge, with only a non-blocking test-description accuracy issue.

The added tests do not change production behavior, but one test claims undefined-input coverage while asserting only the null case.

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 session-description conversion coverage, with one test title overstating the null/undefined cases actually exercised.
packages/recorder-core/tests/recorder-utils.test.ts	Adds focused coverage for recording-mode detection and capture error classification without introducing a concrete behavioral defect.

Prompt To Fix All With AI

### Issue 1
apps/chrome-extension/src/shared/webrtc.test.ts:81
**Test overstates missing-input coverage**

The test claims to cover both `null` and `undefined`, but its only invocation passes `null`. This makes the suite communicate coverage it does not provide.

```suggestion
	it("throws error when session description is null", async () => {
```

---

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.

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[greptile-apps]

Test overstates missing-input coverage

The test claims to cover both null and undefined, but its only invocation passes null. This makes the suite communicate coverage it does not provide.

Suggested change

	it("throws error when session description is null or undefined", async () => {
	it("throws error when session description is null", async () => {

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

Comment:
**Test overstates missing-input coverage**

The test claims to cover both `null` and `undefined`, but its only invocation passes `null`. This makes the suite communicate coverage it does not provide.

```suggestion
	it("throws error when session description is null", async () => {
```

---

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