fix: stabilize v0.2.2 publishing flow, markdown rendering, and wikilink detection

[blackstorm]

Summary

This PR consolidates the v0.2.2 fixes across backend rendering, console
indexing controls, Obsidian plugin sync behavior, and wikilink note
discovery.

What Changed

• Enabled GFM extensions in backend markdown rendering:
  • Tables
  • Task lists
  • Strikethrough
• Added highlight.js theme integration and aligned code block styling with
  typography prose styles.
• Prevented Console pages from being indexed by search engines:
  • Added <meta name="robots" content="noindex, nofollow"> to full Console
    templates.
  • Added X-Robots-Tag: noindex, nofollow response header middleware for
    Console routes.
• Hardened Obsidian plugin sync behavior when publish config is missing:
  • Skip sync operations if Publish URL or Publish Key is not
    configured.
  • Show a clear notice for manual publish actions when config is
    incomplete.
• Improved plugin settings UX by prepopulating the Publish URL input with
  saved value.
• Fixed wikilink detection query in DB layer:
  • Updated SQL LIKE pattern from %[[%]] to %[[%]]% so wikilinks are
    matched anywhere in note content.
• Added/updated tests for the above behaviors (markdown rendering, noindex
  protections, plugin sync guard, and wikilink query).

Why

These changes improve publishing reliability and correctness:

• Markdown output now matches expected Obsidian/GFM features.
• Console pages are less likely to be accidentally indexed.
• Plugin no longer attempts invalid sync calls when not configured.
• Wikilink-based note discovery no longer misses links that are not at the
  end of content.

Validation

• make backend-test
• Result: Ran 181 tests containing 807 assertions. 0 failures, 0 errors.

Breaking Changes

• None.

Migration

• None.

Release Title

v0.2.2

Release Notes

This release focuses on publishing reliability, markdown correctness, and
sync safety.

Highlights

• Added GFM markdown support on the backend (tables, task lists,
  strikethrough).
• Improved code block highlighting integration with app typography styles.
• Added noindex protections for Console pages (meta tags + X-Robots-Tag
  header).
• Prevented plugin sync attempts when Publish URL/Key are missing.
• Improved plugin settings UX by pre-filling the Publish URL.
• Fixed wikilink note filtering to match links anywhere in note content.

Fixes Included

• Backend markdown renderer now enables GFM extensions.
• Console templates now include noindex, nofollow robots meta tags.
• Console responses now include X-Robots-Tag: noindex, nofollow.
• Obsidian plugin now skips sync when publish config is incomplete and shows
  user-facing guidance.
• Wikilink SQL pattern corrected from %[[%]] to %[[%]]%.

Notes

• No breaking changes.
• No database migration required.