Preserve typed link text in pipe-less wikilinks

[JeroenDeDauw]

Fixes #47

Pipe-less [[...]] links now display the target text as typed (like wikitext and Obsidian) instead of the normalized title; the resolved title still drives the href and link registration. Linktrail ([[page]]s) is deliberately not implemented: it is a language-dependent wikitext-ism absent from markdown ecosystems, and [[page|pages]] covers the need.

_{AI-authored — Claude Code, Opus 4.8 (max); detailed brief from @JeroenDeDauw's Fable orchestration session (typed-text and declined-linktrail decisions architected there), implemented here without revision; diff not yet human-reviewed; TDD with each test seen failing first, 284 standalone unit + 430 MediaWiki-integration tests green locally, phpcs/phpstan/psalm clean, markdown↔wikitext parity confirmed via action=parse; CI green.}

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.41%. Comparing base (a1b8d20) to head (d3865c0).

Additional details and impacted files

@@             Coverage Diff              @@
##             master      #48      +/-   ##
============================================
+ Coverage     83.34%   83.41%   +0.06%     
+ Complexity      417      416       -1     
============================================
  Files            40       40              
  Lines          1069     1067       -2     
============================================
- Hits            891      890       -1     
+ Misses          178      177       -1     

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