Bundle native PlantUML builds to stay self-contained

[sproott]

Replace the Java-based PlantUML setup with native executable support for Linux x64, macOS ARM64, and Windows x64.

• Base build infrastructure on new Alma.Build package
• Add native archive download, checksum verification, extraction, and executable smoke testing to the build.
• Move macOS support to ARM64; x64 is no longer supported due to PlantUML native distribution constraints.
• Extend shared console build specs with RuntimeMode and PublishSingleFile. Build and test targets support portable, auto-detected, or explicitly selected RIDs, and release packaging can opt out of single-file publishing (which didn't work out-of-the-box tuc-console).
• Render diagrams using the resolved native executable, removing the tracked JAR and system JRE requirement.
• Package each RID-specific PlantUML archive with its license, notice, and source-provenance files.
• Update update.sh to manage the manifest, provenance, and required GPL notices.