PHLEGM v9 r8 - PCRE2 manifest StrictMode optional-property repair
===================================================================
Input log: PHLEGM-v9-Compiler-Logs-2026-1012-1756-2672.zip
Source: PHLEGM v9 r7 Developer Distribution and matching Bootstrap Archive.

Observed: all Windows 32/64 OpenGL/D3D11 builds terminate before native
compilation with "The property 'packageUrl' cannot be found on this object."

Cause: r7 replaced the legacy scalar packageUrl with packageUrls in
Runtime-Dependencies.json. Its PowerShell downloader nevertheless accessed
BOTH $Spec.packageUrls and $Spec.packageUrl unconditionally. Under strict
property checking, even @($Spec.packageUrl) raises an exception if the
property is missing.

Fix: iterate the optional manifest keys only when a PSObject property exists,
then flatten source values, reject non-HTTPS URIs, preserve priority and
unique URLs, retry candidates, and enforce pinned SHA-256 and cache behavior.
This avoids changing the manifest or silently discarding mirror fallback.

Regression: tests/PHLEGM-PCRE2-Mirror-Fallback.Tests.ps1 now runs in
Set-StrictMode -Version Latest. It exercises modern, legacy, mixed,
missing-field and invalid-scheme manifests, simulated HTTP 403 fallback,
SHA-256 checks and cache corruption. Run on Windows with PowerShell 5.1:

  powershell.exe -NoProfile -ExecutionPolicy Bypass -File tests/PHLEGM-PCRE2-Mirror-Fallback.Tests.ps1

No behavior changes to AA / embedded FBVM / regex matching / Linux PCRE2
resolver / runtime microcode / shared compiler UI or bootstrap.

Runtime matrix and End-User distribution still require successful real
Windows FreeBASIC compiles and PCRE2 dependency staging on the target host.
