Address CPANTS Kwalitee issues

[toddr-bot]

What

Address all 7 failing CPANTS Kwalitee metrics identified at
https://cpants.cpanauthors.org/release/TODDR/XML-Parser-2.57

Why

CPANTS Kwalitee scores affect distribution discoverability and signal
quality to downstream users. The core metric (has_license_in_source_file)
directly impacts the Kwalitee score.

How

Core fix: Added =head1 LICENSE section to Parser.pm with the
standard Perl license text.

Extra fixes:

• Added use warnings to Expat.pm (the namespace() and eq_name()
  methods already had local no warnings 'numeric' blocks)
• Added provides to META_MERGE in Makefile.PL, using dynamic version
  extraction via MM->parse_version() to avoid hardcoding

Experimental fixes:

• Added SECURITY.md with vulnerability reporting contact
• Added CONTRIBUTING.md with contribution guidelines

Regenerated README.md (from updated POD) and MANIFEST.

Testing

Full test suite passes (make test). Verified META provides appear
correctly in generated MYMETA.json.

---

Quality Report

Changes: 7 files changed, 265 insertions(+), 3 deletions(-)

Code scan: clean

Tests: passed (OK)

Branch hygiene: clean

Generated by Kōan post-mission quality pipeline

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.40%. Comparing base (4ee8e6f) to head (ac4856b).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #267   +/-   ##
=======================================
  Coverage   76.40%   76.40%           
=======================================
  Files           1        1           
  Lines        1102     1102           
  Branches      346      346           
=======================================
  Hits          842      842           
  Misses         52       52           
  Partials      208      208           

Flag	Coverage Δ
perl	76.40% <ø> (ø)
xs	76.40% <ø> (ø)

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