fix: handle network errors in saveProject (#4276)

[PS01K]

Issue:

Fixes #4276

When saving a project (PUT /projects/:id for updates or POST /projects for new sketches) fails due to a network error, request timeout, or server disconnection, Axios creates an error object where error.response is undefined.

Previously, both .catch() handlers in saveProject() directly accessed response.status (if (response.status === 403) ...) and response.data (dispatch(projectSaveFail(response.data))). Because response is undefined, this threw an unhandled TypeError: Cannot read properties of undefined (reading 'status'), causing an unhandled promise rejection instead of gracefully executing save failure handling.

Changes:

• client/modules/IDE/actions/project.js:
  • Guarded response?.status === 403 and response?.status === 409 checks in both update (PUT) and creation (POST) catch blocks using optional chaining.
  • Safely passed response?.data to projectSaveFail(response?.data).
• client/modules/IDE/actions/project.unit.test.js:
  • Added unit test suite covering saveProject for existing project update and new project creation under network error conditions (error.response undefined), verifying that endSavingProject, toast notification, and projectSaveFail are dispatched without throwing TypeError.
  • Verified 403 and 409 error modal responses continue to work as expected.

I have verified that this pull request:

• has no linting errors (npm run lint)
• has no test errors (npm run test)
• has no typecheck errors (npm run typecheck)
• is from a uniquely-named feature branch and is up to date with the develop branch.
• is descriptively named and links to an issue number, i.e. Fixes #4276
• meets the standards outlined in the accessibility guidelines

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