PHRASING_ELEMS missing <u>, <s>, and <bdi> elements causes paragraph splitting

Problem

The PHRASING_ELEMS array is missing several HTML5 phrasing content elements: U, S, and BDI.

This causes Readability to incorrectly treat these inline elements as block-level, splitting paragraphs around them.

Example

Input HTML:

<p>Seigneur, mon Die<u>u</u> et mon salut</p>

Output (incorrect):

<p>Seigneur, mon Die</p><u>u</u><p> et mon salut</p>

The <u> tag is being treated as a block element, breaking the paragraph into three parts.

Solution
Add the missing phrasing content elements to PHRASING_ELEMS:

 PHRASING_ELEMS: [
   // ... existing elements ...
  "BDI",  // Bidirectional text isolation
  "S",    // Strikethrough
  "U",    // Underline
   // ...
 ]

Per HTML spec, these are all valid phrasing content elements that should be kept inline within paragraphs.

Search the codebase for the PHRASING_ELEMS array and inspect the tests covering paragraph splitting or phrasing elements. Add BDI, S, and U to the array, then run the relevant test suite and confirm that the example remains one paragraph while existing behavior is unchanged.