fix: ignore wiki-link matches spanning inline code

[brawliscool]

Fixes #269

Summary

• ignore reference matches that overlap inline or fenced code when references_in_codeblocks is disabled
• prevent separate `[[` and `]]` spans from being combined into a false wiki-link
• ignore complete wiki-links used as literal syntax inside inline code
• preserve valid wiki-links directly adjacent to inline code
• preserve the existing references_in_codeblocks = true opt-in behavior

Verification

• cargo test - 78 passed
• cargo fmt --check
• git diff --check

Bounty

/claim #269

[brawliscool]

/claim #269