feat(prettier-plugin-liquid): support prettier-ignore-start / prettier-ignore-end ranges

[SinhSinhAn]

What is this PR?

This PR adds support for range-based formatting ignores (prettier-ignore-start / prettier-ignore-end) to the Liquid prettier plugin. Currently, the plugin only supports single-node ignores with <!-- prettier-ignore --> or {% # prettier-ignore %}, which means if you want to preserve the formatting of a multi-node block, you have to add a separate ignore comment before every single node. That gets noisy fast, especially in larger templates with intentional whitespace or layout.

What was the issue?

Issue #1150 describes the problem well: there's no way to tell the formatter "leave this entire section alone." The only workarounds are per-node prettier-ignore comments (verbose) or .prettierignore for the whole file (too coarse).

Standard Prettier supports prettier-ignore-start / prettier-ignore-end for HTML, but the Liquid plugin didn't implement it.

How does this PR address it?

The implementation builds on the existing prettier-ignore infrastructure. The plugin already has functions that detect ignore comments and a code path in printChild that outputs raw source text for ignored nodes. I extended this with three changes:

1. Detection functions in printer/utils/node.ts: Added isPrettierIgnoreRangeStartNode and isPrettierIgnoreRangeEndNode that recognize both HTML comments (<!-- prettier-ignore-start -->) and Liquid inline comments ({% # prettier-ignore-start %}), following the same dual-format pattern as the existing single-node ignore.

2. Range resolution via isInsidePrettierIgnoreRange: When the printer asks "should this node be printed raw?", this function walks backward through the node's siblings looking for an unmatched prettier-ignore-start. If it finds one before finding a prettier-ignore-end (or running out of siblings), the node is inside a range and gets printed as raw source text. The start and end comment nodes themselves are also printed raw.

3. Test fixtures covering the key scenarios: HTML comment ranges, Liquid comment ranges, nodes outside the range still being formatted, multiple ranges in the same parent, and ranges spanning several different node types.

Both syntaxes are supported:

<!-- prettier-ignore-start -->
<div class="custom-layout">
  {{ some_variable | complicated_filter: foo: bar }}
  {% render 'component', foo: bar %}
</div>
<!-- prettier-ignore-end -->

{% # prettier-ignore-start %}
<div class="custom-layout">
  {{ some_variable | complicated_filter: foo: bar }}
  {% render 'component', foo: bar %}
</div>
{% # prettier-ignore-end %}

Test plan

• New test suite (prettier-ignore-range) passes with 5 test cases
• Existing liquid-prettier-ignore tests still pass (single-node ignores unaffected)
• Both HTML comment and Liquid comment syntax work
• Nodes outside the range are formatted normally
• Multiple ranges in the same parent work independently

Closes #1150