Centralize tested profiles and add read-only diagnostics

[antono3]

Centralize the existing tested compiler/bootstrap and dependency profiles in compatibility.json, and resolve them before CI checkout. Reject disagreement with VPM declarations while preserving advisory upstream-master lanes.

Add read-only compiler/tool/module diagnostics with recovery actions, explicit compiler-profile selection, optional Vulkan device enumeration and JSON support reports. Document upgrade validation.

Move Windows bootstrap pins into the manifest and connect prebuilt-demo compiler/module/native-runtime pins. Stage new tool/check-out caches transactionally; test interrupted downloads, failed clones, incomplete caches and user-file preservation.

Validation: local compatibility and diagnostic regressions, applicable Windows recovery/setup fixtures, workflow actionlint and whitespace checks passed. Full latest-head CI and agent code review are required before merge. Compiler and module versions are unchanged.

[antono3]

Agent code review of 801205f.

Reviewed manifest/declaration agreement, immutable compiler/bootstrap pins, workflow checkout paths and profile selection, installed-tag verification, bounded read-only diagnostics and failure-oriented regression fixtures. Existing compiler/dependency versions and advisory lanes are preserved. No blocking findings. Reviewed transactional staging, atomic cache commit, scoped cleanup and preservation of working/user-modified caches. Local Windows recovery fixtures passed.

All 25 applicable PR checks and complete latest-head workflows passed. This is agent review, not independent human approval.