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 WebRTC session-description conversion and several shared recorder utility behaviors.

• Adds offer, answer, and missing-description assertions for the Chrome extension WebRTC helper.
• Adds recorder-core coverage for recording-mode detection, cancellation classification, and display-media retry classification.

Confidence Score: 4/5

The PR appears safe to merge, with only a non-blocking gap in the advertised undefined-input coverage.

The changes affect tests only, and the sole accepted concern is that one test names two nullish inputs 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 useful WebRTC conversion coverage, but the null-or-undefined case exercises only null.
packages/recorder-core/tests/recorder-utils.test.ts	Adds valid coverage for recording-mode and capture-error utility behavior without introducing a functional issue.

Prompt To Fix All With AI

### Issue 1
apps/chrome-extension/src/shared/webrtc.test.ts:83-85
**Undefined case remains untested**

This test claims to cover both null and undefined descriptions but invokes `toSessionDescriptionInit` only with null, so an undefined-input regression would leave the suite green despite the advertised coverage.

```suggestion
		expect(() => toSessionDescriptionInit(null)).toThrow(
			"Missing session description",
		);
		expect(() => toSessionDescriptionInit(undefined)).toThrow(
			"Missing session 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 to cover both null and undefined descriptions but invokes toSessionDescriptionInit only with null, so an undefined-input regression would leave the suite green despite the advertised coverage.

Suggested change

	expect(() => toSessionDescriptionInit(null)).toThrow(
	"Missing session description",
	);
	expect(() => toSessionDescriptionInit(null)).toThrow(
	"Missing session description",
	);
	expect(() => toSessionDescriptionInit(undefined)).toThrow(
	"Missing session 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: 83-85

Comment:
**Undefined case remains untested**

This test claims to cover both null and undefined descriptions but invokes `toSessionDescriptionInit` only with null, so an undefined-input regression would leave the suite green despite the advertised coverage.

```suggestion
		expect(() => toSessionDescriptionInit(null)).toThrow(
			"Missing session description",
		);
		expect(() => toSessionDescriptionInit(undefined)).toThrow(
			"Missing session description",
		);
```

---

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