feat(libc): implement getprogname

[MarcZX10]

What

Implement getprogname for the PS5 process image name (eboot.bin), matching the existing __progname value exposed by libkernel. Add a registered guest test for the returned name.

Tested

Linux, GCC 12.2.0: guest_program_name passed; conventions check and git diff --check passed. The auxiliary test-registration script requires Ninja, which is unavailable in this environment.

Checklist

• Based on current main; no open PR implements getprogname
• One topic per PR
• No comments or investigation files added
• Generic PS5 process-name behavior
• Depends on: none
• AI-assisted: yes

[MarcZX10]

Update: the five PR heads were rebased onto main at fe9beae0. Upstream has since advanced to 4d03ecf4; the latest merge only changes libSceVideoOut/src/VideoOutDriver.cpp. None of these PRs touches that file, and local merge-tree checks still show all five integrate cleanly.

I reran each focused Linux build/test, conventions, and diff checks on the current PR heads; all passed. The current Build, Conventions, and Progress report runs remain action_required with no jobs for all five heads. Could a maintainer approve them so upstream CI can run? The #1591 and #1592 tests are isolated from #1490’s GuestStrings.cpp changes. Windows CI remains unverified locally.

[MarcZX10]

Closing for now based on the maintainer’s current evidence bar on the adjacent import-audit PRs: #1578 lists this export, but no title is shown calling it on current main. Reopen when a title stops here during a real run, with the log line.