In order to fix custom croppable shapes crashing when cropped (#7927),
this PR prevents `getCropBox` from adding `isCircle: undefined` to the
result crop object.

The `isCircle` property was introduced for circle crops on image shapes.
However, `getCropBox` was unconditionally copying it onto every result
crop via `isCircle: crop.isCircle`. When the input crop didn't have
`isCircle` set, this produced `{ isCircle: undefined }` — and
`Object.keys()` includes keys with `undefined` values. Custom shapes
with their own crop validators (without an `isCircle` field) would then
fail with `ValidationError: Unexpected property` at `isCircle`.

The fix only copies `isCircle` when it was explicitly set on the input
crop (`!= null`).

Closes #7927
Based on the fix from #7926 by @jamesbvaughan.

### Change type

- [x] `bugfix`

### Test plan

1. Create a custom croppable shape without `isCircle` in its crop
validator
2. Crop the shape — should no longer crash

- [x] Unit tests

### Release notes

- Fixed a crash when cropping custom shapes that don't include
`isCircle` in their crop schema

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Small, localized change to crop serialization plus added tests; main
risk is minor behavior change for callers that implicitly relied on
`isCircle` always being present.
> 
> **Overview**
> Fixes a cropping regression where `getCropBox` would always copy
`crop.isCircle` into the returned crop object, causing `isCircle:
undefined` to appear and break custom shape crop validators.
> 
> `getCropBox` now only includes `isCircle` in the output when it’s
explicitly set (non-null/undefined) on the input crop, and new unit
tests cover absence/undefined cases plus validation against a custom
crop schema without `isCircle`.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
b6c7164. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Co-authored-by: James Vaughan <[email protected]>
Co-authored-by: Claude Opus 4.6 <[email protected]>

In order to keep release documentation current after the v4.3.2 patch
release, this PR updates both the archived and next release notes.

### Changes

**v4.3.0.mdx:**
- Add GitHub release link for v4.3.0
- Add v4.3.1 patch section (draw shape delta encoding precision fix)
- Add v4.3.2 patch section (custom shape crop fix)

**next.mdx:**
- Update `last_version` from v4.3.1 to v4.3.2
- Add bug fix entries for #7938 (paste-into-frame) and #7931 (crop
isCircle)

### Change type

- [x] `docs`

### Test plan

- [ ] Verify release notes render correctly on the docs site

### Release notes

- Update release notes with v4.3.1 and v4.3.2 patch entries

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Docs-only updates to markdown release notes; no runtime code changes,
with minimal risk beyond potential formatting/rendering issues.
> 
> **Overview**
> Updates release documentation to reflect the `v4.3.2` patch.
> 
> Bumps `apps/docs/content/releases/next.mdx` `last_version` to `v4.3.2`
and adds two new bug-fix entries (paste-into-frame parenting and a
custom-shape cropping crash).
> 
> Extends `apps/docs/content/releases/v4.3.0.mdx` with GitHub release
links and a new **Patch releases** section covering `v4.3.1` and
`v4.3.2`.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
ee7dc07. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

In order to keep release documentation current after the v4.3.2 patch
release, this PR updates both the archived and next release notes.

### Changes

**v4.3.0.mdx:**
- Add GitHub release link for v4.3.0
- Add v4.3.1 patch section (draw shape delta encoding precision fix)
- Add v4.3.2 patch section (custom shape crop fix)

**next.mdx:**
- Update `last_version` from v4.3.1 to v4.3.2
- Add bug fix entries for #7938 (paste-into-frame) and #7931 (crop
isCircle)

### Change type

- [x] `docs`

### Test plan

- [ ] Verify release notes render correctly on the docs site

### Release notes

- Update release notes with v4.3.1 and v4.3.2 patch entries

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Docs-only updates to markdown release notes; no runtime code changes,
with minimal risk beyond potential formatting/rendering issues.
> 
> **Overview**
> Updates release documentation to reflect the `v4.3.2` patch.
> 
> Bumps `apps/docs/content/releases/next.mdx` `last_version` to `v4.3.2`
and adds two new bug-fix entries (paste-into-frame parenting and a
custom-shape cropping crash).
> 
> Extends `apps/docs/content/releases/v4.3.0.mdx` with GitHub release
links and a new **Patch releases** section covering `v4.3.1` and
`v4.3.2`.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
ee7dc07. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->