PHLEGM v8 checkpoint 44 - PET/CBM End User distribution packaging fix

Source baseline: PHLEGM v8 Checkpoint 43. All machine/CPU definitions unchanged.
Changes in tools/Build-PHLEGM-v8.ps1:
- Recognize descriptive checkpoint carrier names and extract the trailing timestamp.
- Resolve Developer distribution root as the ZIP parent, placing End-User ZIPs beside the Developer distribution.
- Account for mandatory SDL2-32.dll / SDL2-64.dll in Windows End User minimal archives.
- Allow accompanying SDL2-LICENSE.txt only when Windows SDL2 runtime is present.
- Reject unexpected runtime DLLs, require declared runtime(s) for selected Windows architectures.
- Remove failed / partially verified ZIP and checksum sidecars rather than leaving bad deliverables.

Verification performed: ZIP member integrity and canonical carrier layout, manifest path,
source-preservation diff (only changed builder and this note), regex/path/entry-set checks.
Not performed: Windows PowerShell execution, native FreeBASIC builds, or actual runtime launches.
If a fresh build still fails, obtain the new Compiler-Logs ZIP for the exact failure.
