[koushiro]

Which issue does this PR close?

Closes #.

Rationale for this change

Upgrade Hawkeye from v6 to v7.2.0.

What changes are included in this PR?

• Install Hawkeye 7.2.0 with taiki-e/install-action in the license and Python stub-generation workflows.
• Migrate licenserc.toml to the v7 schema while preserving existing exclusions.
• Add custom XML and Maven batch styles to preserve existing header formatting and reduce migration diffs.
• Standardize Go license headers on // comments to keep Hawkeye and gofmt compatible, including files with build constraints.
• Update Python formatting commands for the v7 CLI and retain their directory scope.
• Normalize license headers where required by v7.

Are there any user-facing changes?

No

Breaking changes

AI Usage Statement

• Harness: Codex desktop.
• Model: gpt-6.1-sol
• Effort: high
• Role: Assisted with the CI and configuration migration, license-header compatibility investigation, local validation, and PR description drafting.