Ignore wikilink markers overlapping inline code

[sk8kpwhrjt-creator]

Fixes #269

/claim #269

Summary

• add a range-overlap helper so references that touch inline or fenced code spans can be filtered when references_in_codeblocks is disabled
• filter references by overlap with code spans instead of only full containment, which removes the false wikilink created by literal inline-code [[ and ]] markers
• keep adjacent real wikilinks intact with a regression test

Verification

• cargo fmt --check
• cargo test inline_code -- --nocapture
• cargo test
• git diff --check