Sort names with particles per each style's demote setting

[dknauss]

Summary

Closes #142. Before this change, a surname opening with a lowercase particle ("van Duijnhoven", "de la Cruz", "von Neumann", "d'Alembert") sorted under the particle in every style.

Now each bundled style's demote-non-dropping-particle setting decides:

• Chicago (both styles) and Vancouver sort by the surname proper. For Chicago, the formatter also splits the particle out before citeproc-php renders, so the entry reads "Duijnhoven, Elza van" and sorts under D.
• APA, MLA, Harvard and the rest keep the particle in front and still sort under V.
• Capitalized forms ("Van Buren") are part of the surname and are never split.

No data-shape change. Names stay stored as entered, and the particle is worked out at sort and format time. BibTeX/RIS export, JSON-LD, COinS, Edit fields and dedup are unchanged.

New code:

• src/lib/name-particles.js holds the shared particle rules.
• The style registry gains demoteNonDroppingParticle.
• The sorter takes a particleAwareSort option.
• The PHP save port in includes/save-markup.php mirrors all of it.

Compatibility. save() order changes, so a new deprecated[0] freezes the pre-1.12.0 shape. Existing posts stay valid and take the new order the next time they are saved. The formatter cache key is bumped to version 3.

Validation

• npm run lint:js, lint:css, lint:i18n: pass
• composer lint:php, composer analyze:php: pass
• Jest: 1049 passed, 2 skipped. New tests:
  • name-particles.test.js, including a check that each registry entry matches its bundled CSL file;
  • deprecation fixture v13;
  • sort-coordination cases 14–17;
  • the citeproc-js conformance particle fixtures, now un-excluded.
• PHPUnit: 440 tests pass (only the known vendor deprecations reported).
  • New tests cover the split, sort_family and prepare_csl_for_formatter.
  • SortCoordinationTest now prepares items the way the formatter does.
  • The save-parity fixtures (collation-mix, mla-repeated-authors) were regenerated from the PHP port, and JS parity is 20/20.
• npm run build and npm run package:release succeed. composer verify:metrics passes, with the metrics doc updated.

Checklist

• Tests added/updated
• CHANGELOG [Unreleased] entry
• Docs/metrics updated
• Saved-content compatibility covered by a deprecation

🤖 Generated with Claude Code

https://claude.ai/code/session_01KbVuMPN7YTcV27vwsG3LZ2

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Generated by Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 89.72603% with 15 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.88%. Comparing base (b8be70b) to head (7aa36ec).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/lib/name-particles.js	60.00%	0 Missing and 12 partials ⚠️
src/lib/sorter.js	81.25%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #147      +/-   ##
============================================
+ Coverage     87.87%   87.88%   +0.01%     
  Complexity       22       22              
============================================
  Files            59       60       +1     
  Lines          6952     7060     +108     
  Branches        678      690      +12     
============================================
+ Hits           6109     6205      +96     
  Misses          292      292              
- Partials        551      563      +12     

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