feat(libkernel): implement POSIX mprotect

[kjhq]

What

Adds the POSIX mprotect export next to mmap and munmap in PosixMemory.cpp. It calls DoMprotect, the same path as sceKernelMprotect (which rounds the range out to guest pages, updates the allocation tracker and the host protection), and follows the POSIX error convention of its neighbours: -1 with errno.

• zero length: 0, nothing changes (as FreeBSD)
• null address or a range that wraps: EINVAL
• a range DoMprotect rejects (it throws): EINVAL; std::bad_alloc: ENOMEM

The protection value is passed through unchanged, as sceKernelMprotect does.

guest_memory gains checks: zero length succeeds, a null address is EINVAL, an unaligned one-byte range makes its page read-only (the tracker reports it readable and not writable, and it can still be read), and protection can be restored to read-write.

Title

PPSA17221 (Minecraft) needs #716 to load the modules in its app root, so every run below is current main + #716 + the PRs of this set (#1088, #1090–#1096), plus local changes outside it: dialog, NpAuth and TextToSpeech2 stubs that open PRs cover (#560, #925, #301) and a GPU end-of-pipe change that is not submitted. With all of them the title loads a world. The line below is from a run with only this PR left out, Windows 11, WinLibs GCC, normal user session.

Without it startup stops at load:

FAIL: unresolved ELF import YQOfxL4QfeU from libkernel.prx

YQOfxL4QfeU is mprotect, imported by the title's libcohtml.Prospero.prx.

Tested

Debian 13 (WSL2), GCC 14.2.0, Release: full ctest 390/390 passed (GPU tests skipped: no Vulkan device in WSL), including guest_memory.

Windows 11, WinLibs GCC: PPSA17221 with this PR and the rest of the set loads a world (runs described above). Not tested with Windows ctest.

Checklist

• Based on current main; no other open PR implements the same functions
• One topic per PR; follow-ups go in a new PR
• No comments in code except technical debt
• Unimplemented paths throw (NotImplemented_nid_no_patch); silent stubs are listed in TechnicalDebt
• No notes, investigation .md files or images added to the repository (attach them to this PR)
• New third-party code is a submodule built from source
• Generic behaviour, not specific to one title
• Depends on: none
• AI-assisted: yes

🤖 Generated with Claude Code

[github-actions]

Progress report (c3f4db7 → 53a31b5)

➖ System libraries: 85.22% (+0.0%, +1 implemented functions)

✅ 1 implemented

Library	Name
libkernel	mprotect_nid_postfix

[adriadam10]

Checked build + full ctest on current main with this PR (419/419); guest_memory fails to link with the PosixMemory.cpp change reverted. Error codes follow FreeBSD kern_mprotect (sys/vm/vm_mmap.c): only protection failure, resource shortage and out-of-bounds get their own errno, so an unmapped range ends up as EINVAL (ENOMEM is the Linux behaviour).

Added one commit on top (tests only): mprotect on an unmapped range and on a range that wraps the address space both return -1/EINVAL.

Merging once CI is green.