Add AROS aarch64 build + packaging lane with minimal platform-condition updates

[Copilot]

This PR prepares the bootstrap/release toolchain for an AROS aarch64 target by extending existing AROS-specific paths rather than introducing parallel logic. The update keeps existing AmigaOS/MorphOS/AROS lanes intact while adding detection/configuration for a sixth build/package lane.

• Build system: new AROS aarch64 lane

  • Added Makefile.aros-aarch64 aligned with existing AROS lane conventions.
  • Uses aarch64-aros-* toolchain names and the same stack-cookie/post-link flow as current AROS targets.
  • Made SDK GCC path discovery version-agnostic (no hardcoded GCC subversion).

• Platform conditional update (AROS console CSI behavior)

  • Extended include/tg_console_ui.h so AROS aarch64 follows the modern ESC [ CSI path (same behavior class as AROS x86_64), while preserving legacy i386 behavior.

• Release packaging updates

  • Extended scripts/package-human-release.sh with:
    • AROS_AARCH64_BINARY input path
    • aros-aarch64 package lane
    • AROS Archives artifact mapping for aarch64
    • aarch64 architecture detection/validation patterns consistent across package checks and archive-content checks.

• Candidate packaging + verification

  • Extended scripts/package-test-candidate.sh from five lanes to six:
    • new CLI arg for aarch64 ISO label
    • uniqueness validation, drawer assembly, ZIP/ISO generation, hash listing, and ISO content verification for AROS-aarch64.
  • Extended scripts/verify-release.sh with aros-aarch64-alpha-* artifact verification.

• Documentation

  • Updated README.md platform/build-lane descriptions to include AROS aarch64 and the new Makefile path.

/* include/tg_console_ui.h */
#if defined(__AROS__) && !defined(__x86_64__) && !defined(__aarch64__)
#define TG_UI_CSI "\x9b"
#else
#define TG_UI_CSI "\033["
#endif

[bohunamiga]

added support for aarch64