Add test fixture for short text in wide containers, document test runner

- Add short-text-in-wide-container examples to quality-should-pass fixture
- Add Testing section to CLAUDE.md
- Revert unnecessary line-length estimatedLines guard (textLen > 80 already sufficient)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -42,6 +42,14 @@ Source files use placeholders that get replaced per-provider:
 - `{{config_file}}` - Config file name (CLAUDE.md, .cursorrules, etc.)
 - `{{ask_instruction}}` - How to ask user questions
 
+## Testing
+
+```bash
+bun run test       # Run all tests
+```
+
+Unit tests (build, detector logic) run via `bun test`. Fixture tests (jsdom-based HTML detection) run via `node --test` because bun is too slow with jsdom. The `test` script handles this split automatically.
+
 ## CLI
 
 Impeccable includes a CLI for running anti-pattern detection outside of AI harnesses:

tests/fixtures/antipatterns/quality-should-pass.html

@@ -121,6 +121,12 @@
     <p class="good-measure">This paragraph has a max-width of 65ch, keeping the line length comfortable for reading. The eye can easily track from the end of one line to the beginning of the next.</p>
   </div>
 
+  <h2>Short Text in Wide Container (OK)</h2>
+  <div class="demo">
+    <p style="max-width: none; width: 100%;">This is a short sentence in a wide container.</p>
+    <p style="max-width: none; width: 100%;">Just a few words here.</p>
+  </div>
+
   <h2>Good Padding</h2>
   <div class="demo">
     <div class="good-padding">This container has 16px padding, giving the text room to breathe within its border.</div>