fix(libkernel): allow sceKernelMprotect on committed host memory outside the guest registry

[xXPBSXx]

What

sceKernelMprotect threw "guest protection or unmap range is not registered" for committed private host memory that is not in the guest allocation registry (seen on a thread stack: 0xf8380000+0x580000, prot 0xc2). On Windows it now sets the native protection for such a range and returns 0 when the range is a committed private region that does not overlap any registered guest allocation. Everything else keeps its previous path. Related: #3143.

Tested

• Windows 10, MinGW/Ninja build of main a11c8f7 plus this commit: ctest -R "^guest_memory$" passes, including the new CheckMprotectOfHostMemoryOutsideTheGuestRegistry (VirtualAlloc'd region: protect to read/write, write and read back, read-only, read/write again, native protection checked with VirtualQuery). That check failed before the change (verified on the earlier branch version). python tools/check_conventions.py --base upstream/main passes.
• Found with Resident Evil 4 (PPSA07411) earlier (the range was a thread stack); this exact branch was not run with the title. Not tested: Linux/macOS (the change is _WIN32 only).

Checklist

• Based on current main; no other open PR implements the same functions (perf(agc): cache page permissions within registered allocations #1330, feat(memory): track changes to mapped address ranges #1360 and fix(build): keep libc.prx needed by every executable that links a prx #3684 touch other code)
• 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 (none added)
• No notes, investigation .md files or images added to the repository
• New third-party code is a submodule built from source (none added)
• Generic behaviour, not specific to one title
• Depends on: none
• AI-assisted: yes

🤖 Generated with Claude Code

[adriadam10]

Checked the diff against DoMprotect: the new branch only applies to committed private regions that do not overlap a registered guest allocation (RegionSize >= bytes), everything else keeps its previous path. Linux build and guest_memory pass; the new code and test are _WIN32 only, so the Windows run in the PR description is what covers them. Merging.