PHLEGM v9 r5 - PCRE2 runtime deployment fix

Reported symptom: Definition assignment regex: PCRE2 8-bit shared library is unavailable.
Cause: Windows executables load PCRE2 dynamically, but the end-user build shipped only SDL2.

Runtime contract:
 - Windows 32bit: PCRE2-32.dll beside PHLEGM Windows 32bit executable.
 - Windows 64bit: PCRE2-64.dll beside PHLEGM Windows 64bit executable.
 - Both DLLs may coexist for Combined builds, with explicit architecture checks.
 - Linux uses system libpcre2-8.so.0; Linux ELF distribution does not bundle Windows DLLs.
 - PCRE2 remains generic; parser schema stays in definition-parser.bi and FBVM in aa.lib.

Build process:
 - Downloads pinned MSYS2 PCRE2 binary packages over HTTPS as needed.
 - Verifies package SHA256 and PE machine architecture, extracts only the DLL and license using tar.exe (zstd).
 - Caches DLL in build/runtime/Windows-<bitness>/ for offline subsequent builds.
 - Requires both SDL2 and PCRE2 DLLs in relevant developer compile locations and End-User ZIPs.
 - Fails explicitly if required dependency cannot be acquired or packaged.
 - For offline builds, pre-seed valid PCRE2-32.dll / PCRE2-64.dll in their architecture-specific cache folders.
 - If archive extraction fails, ensure tar.exe supports .tar.zst / use an offline-seeded DLL.

Third-party: PCRE2 BSD-3-Clause; MSYS2 packages with license file.
No PCRE2 binaries are embedded in this source archive; build process acquires them on Windows.
Native Windows compilation and end-user runtime execution need user-side validation.
