chore: migrate HawkEye to v7

[tisonkun]

Which issue does this PR close?

N/A — this is a maintenance migration for the license-header tooling.

Rationale for this change

HawkEye v7 uses a new configuration schema and removes the v6 formatter exit-code behavior. The existing integration would stop working once v7 is installed.

What changes are included in this PR?

• migrate the HawkEye configuration to v7
• install the latest HawkEye release without pinning the tool version
• update the license-header helper for v7 formatter semantics
• normalize the small set of existing headers that v7 recognizes but rewrites canonically

Are these changes tested?

Yes. The repository license-header script passes with HawkEye v7 (1713 files, 0 changes, 0 conflicts, 0 unsupported). Changed YAML, TOML, Bash, and Python files also passed syntax or formatter checks as applicable.

Are there any user-facing changes?

No.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.38%. Comparing base (933710d) to head (5e553c4).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff            @@
##             main   #24578    +/-   ##
========================================
  Coverage   81.37%   81.38%            
========================================
  Files        1116     1116            
  Lines      397661   397960   +299     
  Branches   397661   397960   +299     
========================================
+ Hits       323614   323868   +254     
- Misses      55106    55128    +22     
- Partials    18941    18964    +23     

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[jayzhan211]

👍🏻

[kumarUjjawal]

[license_header.sh] `hawkeye check --config licenserc.toml`
  thread 'main' panicked at hawkeye-6.5.1/src/subcommand.rs:117:52:
  called `Result::unwrap()` on an `Err` value: cannot parse config file: licenserc.toml
  21 | [files]
     |  ^^^^^ unknown field `files`

I think there should be an upgrade script for people with older versions in their system.