Add a realistic Gutenberg blocks fixture for VisualBrief regression tests

[yoldaolmak]

Why

The Gutenberg input is a real editor surface. Its parser needs a representative fixture, not only a minimal string embedded in a test.

Scope

Add one fixture under tests/fixtures/ containing ordinary Gutenberg comments, paragraphs, two H2 headings, inline formatting, and a list or quote block. Add a focused test proving VisualBrief.from_html() extracts the title, H2 targets, and section excerpts.

Reference

• tests/unit/test_wordpress_input.py
• src/pictovap/core/primitives.py (VisualBrief.from_html)

Done when

• The fixture contains no credentials or real private content.
• The test asserts both H2 heading targets and at least one meaningful excerpt.
• pytest tests/unit/test_wordpress_input.py -q --no-cov passes.

No claim is needed. Fork and open a PR directly.

[yoldaolmak]

Maintainer update: this remains a good first issue. Use a synthetic Gutenberg fixture only; it should cover block comments, two H2 headings, inline formatting, and a meaningful excerpt without credentials or private article material. Keep the test at the Visual Brief HTML parsing boundary.