fix: support VC6 precompiled header creation and reuse

[banteg]

VC6 (CL.EXE 6.0 SP5) aborts while creating an automatic precompiled header with /YX /Fprepro.pch: it calls the missing MoveFileExW export with MOVEFILE_COPY_ALLOWED to move its temporary PCH into place. Once that move succeeds, reusing the PCH exposes a second failure: a fixed-address MapViewOfFileEx view is absent from the allocator's address-space bookkeeping, so the next top-down VirtualAlloc can overwrite it. On macOS this reproduced as SIGBUS.

This change implements MoveFileExA/W with atomic no-replace renames, replacement checks, and cross-volume copy/delete fallback, including flushing copied data for MOVEFILE_WRITE_THROUGH. Reboot scheduling and link-tracking flags explicitly return ERROR_NOT_SUPPORTED; invalid flag combinations return ERROR_INVALID_PARAMETER. Fixed-address views now reserve, register, and release their ranges through the existing allocator bookkeeping, rejecting overlaps in both directions.

Adds self-checking file-move and fixed-view collision regressions, plus a small manual VC6 reproducer in test/vc6_pch (compiler supplied by the user).

Validation:

• New/expanded fixtures passed Wine 11.0 first; the fixed-view test reproduced the original overlap before the mapping fix.
• All 49 CTests pass in both macOS debug and release builds.
• ANSI/wide cross-volume moves, replacement, write-through, and directory rejection passed under Wine and both wibo builds using a separate HFS+ test volume.
• VC6 plain compilation, automatic PCH creation, and PCH reuse pass under Wine and both wibo builds. Reuse preserves PCH contents and mtime; all nine object files match after excluding only the COFF timestamp.
• Two full Crimson compiler workloads (statistics_update_check_worker and highscore_sync_worker) also passed Wine/fork × plain/create/reuse: all six objects per function match after COFF timestamp normalization, with unchanged matching metrics.
• Both changed C++ translation units also compile to Linux x86-64 objects with Zig's C++ toolchain. Linux runtime testing remains for CI.
• clang-format and git diff --check pass; clang-tidy reports only existing warnings outside the added code.

The full Wine baseline has four existing fixture expectation failures (shlwapi, gettempfilename, heap, rtl); both native wibo suites are green.