fix(chat): restore table vertical scroll and cell word wrapping

[mrohan-sq]

Summary

Tables in chat responses were cutting off text. Two CSS issues combined to cause this:

1. overflow-y: hidden on the table scroll container overrode Streamdown's default overflow-y: auto, completely disabling vertical scrolling. Combined with Streamdown's default maxHeight: 300px, any table taller than 300px had its bottom rows clipped with no way to scroll.

2. No overflow-wrap on td cells — long unbreakable strings (URLs, file paths, code identifiers) caused horizontal overflow instead of wrapping within cells.

PR #207 (smaller wrapping headers) made this worse: wrapping headers narrow columns → body text wraps more → rows get taller → more content falls below the 300px cutoff.

Changes

• overflow-y: hidden → overflow-y: auto on the table scroll container (globals.css)
• Added overflow-wrap: break-word to td cells (globals.css)
• Updated globals.streamdown-table.test.ts to assert the new behavior

Related issue

none found

Testing

• All existing table-related tests pass (2 table style tests + 2 scrollbar tests + 9 message tests)
• Pre-commit hooks passed (biome, typecheck, i18n, design-system checks, berdctl contract)

[kalvinnchau]

🤖 overflow-wrap: break-word does not reduce a table cell’s intrinsic minimum width under automatic table layout, so long unbroken URLs, paths, or identifiers can still expand the table and scroll horizontally instead of wrapping. I reproduced this in Chromium with a 100-character token: the table remained 749px wide inside a 300px container. overflow-wrap: anywhere kept it at 300px and wrapped the token. Could we use anywhere here and, ideally, cover the rendered behavior with a browser/layout test? The current test only verifies that the CSS declaration exists.

[mrohan-sq]

🤖 Good catch — updated in 084d619.

Changed overflow-wrap: break-word → overflow-wrap: anywhere, which participates in min-content sizing so long unbreakable strings wrap within the cell instead of expanding the table.

Also added a Playwright browser layout test (table-overflow.spec.ts) that verifies:

1. A 200-char unbreakable string in a td wraps within a 300px container (no horizontal expansion)
2. A 50-row table scrolls vertically (scrollHeight > clientHeight, overflow-y: auto)

The browser test uses page.setContent() with inline CSS so it runs from a standalone Playwright config (playwright.table-overflow.config.ts) without needing a built dist/.