fix: chunking dropping table content (#4352)
## Preserve mixed-content tail text in table HTML
### Summary
`HtmlTable.from_html_text` compactification cleared every element's
`.tail`, silently dropping any text between inline children of a `<td>`.
In practice this deleted real content like `": do not..."` after
`<b>NOTICE</b>`, bullet lines following each `<br/>`, and any inter-tag
prose in rich table cells — visible whenever a table was chunked (any
strategy: `basic`, `by_title`, `by_page`).
Pure-whitespace tails are still stripped (those are just pretty-print
indent). Tails carrying content are now kept, with internal whitespace
runs collapsed and a single leading/trailing space preserved so adjacent
text doesn't run together.
### Changes
- `unstructured/common/html_table.py`: replace the blanket `e.tail =
None` with whitespace-aware normalization.
- `test_unstructured/common/test_html_table.py`: two regression tests
covering mixed inline markup, `<br/>`-separated lines, and whitespace
collapsing.
- Bump to `0.22.28` + changelog entry.
<!-- CURSOR_SUMMARY -->
---
> [!NOTE]
> **Low Risk**
> Low risk: localized change to table HTML minification that preserves
previously-dropped text; main risk is minor whitespace/serialization
differences in downstream table chunking output.
>
> **Overview**
> Fixes `HtmlTable.from_html_text()` compactification to **stop deleting
meaningful mixed-content tail text** (text between inline children like
`<b>foo</b> bar` or between `<br/>` siblings), while still dropping pure
formatting/indent whitespace and collapsing internal whitespace runs.
>
> Adds regression tests for mixed inline markup and `<br/>`-separated
cell content, and bumps the library to `0.22.28` with a changelog entry
describing the fix.
>
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
fe27d3582a40cf1d27e8617491d9b1214057605e. Bugbot is set up for automated
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