fix(markdown): clean heading links — wrap text in anchor instead of # marker

[x3ek]

Summary

• Replaces TocExtension(permalink="#") with permalink=False + a custom HeadingAnchorTreeprocessor that wraps heading text in <a class="heading-anchor" href="#id">
• The # marker is gone from all themes; heading text itself is now the link target
• Updates all three bundled themes to style .heading-anchor instead of .headerlink
• Renames test_heading_anchor_uses_hash → test_heading_text_is_anchor_link with updated assertions

Before: <h2 id="hello-world">Hello World<a class="headerlink" href="#hello-world">#</a></h2>
After: <h2 id="hello-world"><a href="#hello-world" class="heading-anchor">Hello World</a></h2>

Closes #68

[Copilot]

Pull request overview

Updates SquishMark’s Markdown rendering so headings link cleanly to their own anchors by wrapping the heading text in an <a class="heading-anchor" href="#...">...</a> instead of rendering a visible # permalink marker, and aligns bundled themes/tests with the new markup.

Changes:

• Adds a custom Python-Markdown treeprocessor/extension to wrap heading contents in a self-referencing anchor while disabling TocExtension permalinks.
• Updates bundled themes to style .heading-anchor (replacing .headerlink styling).
• Updates/renames the markdown heading permalink test to assert the new behavior.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
src/squishmark/services/markdown.py	Adds HeadingAnchorTreeprocessor + extension and switches TocExtension(permalink="#") to permalink=False.
tests/test_markdown.py	Renames and updates the heading anchor test for the new markup.
themes/default/static/style.css	Adds .heading-anchor styling for default theme.
themes/blue-tech/static/style.css	Replaces .headerlink styles with .heading-anchor styles.
themes/terminal/static/css/style.css	Replaces .headerlink styles with .heading-anchor styles.

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[x3ek]

Playwright testing — all three themes verified

Tested locally against all three bundled themes with a fresh browser session (no cache).

HTML structure

<h2 id="stage-1-denial"><a class="heading-anchor" href="#stage-1-denial">Stage 1: Denial</a></h2>

No # marker, no nested anchors, heading text is the link.

Results

Theme	Heading color (computed)	text-decoration	Anchor click → hash
default	rgb(196, 101, 42) (orange, inherited)	none	✓
blue-tech	rgb(255, 255, 255) (white, inherited)	none	✓
terminal	green (inherited)	none	✓

CSS cascade fix confirmed working — anchors inherit the heading color rather than the general link color in all themes.

— Claude