Add Rocky 9.7 V2K build support while keeping single ISO packaging

[dhslove]

Summary

• add Rocky 9.7 V2K build support alongside existing Rocky 9.6 support
• keep a single ISO layout while bundling both v2k-rpm-rocky9.6 and v2k-rpm-rocky9.7
• select the correct V2K repo at install time based on host VERSION_ID
• add rpm/v2k_baseline_pkgs_ablestack_9.7.txt
• use Rocky 9.7 public repositories instead of vault during build

Details

• Rocky 9.6 build path remains unchanged and is still supported
• Rocky 9.7 V2K build path is added in parallel
• baseline handling avoids pulling unnecessary host packages by reusing the ABLESTACK 9.6 baseline model
• if a matching V2K repo is not bundled for the host Rocky minor, the installer warns and skips the V2K add-on instead of failing

Validation

• workflow YAML parsed successfully
• generated install-linux.sh passed bash -n
• install-time V2K repo selection verified for Rocky 9.6 and 9.7
• unsupported minor warning path verified
• build completed successfully