fix: ignore wiki-link markers inside inline code

[NightVibes33]

/claim #269

Summary

• ignore wiki-link markers when the [[ / ]] markers are inside inline code spans
• preserve real wiki links on the same line, including links whose text contains inline-code backticks
• preserve raw fenced-code-block reference parsing for references_in_codeblocks
• add regression tests for the exact inline-code false positive, same-line real links, fenced-code behavior, and real links containing backticks

Issue coverage

This fixes the unresolved-reference false positive for documentation text such as `[[` and `]]`, where bracket markers are examples inside inline code rather than Obsidian wiki links. The filter stays narrow so legitimate links are not dropped just because their link text contains backticks.

Verification

• rustfmt --edition 2021 --check src/vault/mod.rs
• git diff --check

[NightVibes33]

/claim #269