Follow-up to 92da8b2. With `textAlignVertical: center` + `isDense:true`,
the TextField was centering the line-box baseline on the parent
midline — but Latin lowercase glyphs sit at ~75% of line height,
leaving descender space empty below and the optical center of text
visibly above the pill midline.
Fix: `textAlignVertical: TextAlignVertical(y: 0.4)` shifts the
baseline down to align Latin x-height optical centers with the pill
midline. Also added explicit `alignment: Alignment.center` on the
Container so the field's small intrinsic line-box positions on the
midline rather than docking to the top.
Verified on emulator-5556 driving the typed "halo" through the chat
input — text body now sits on the visual midline of the 44dp pill.
The horizontal underline below typed text is Gboard's composing-
region indicator (Android IME behavior), not a TextField underline,
and will go away once the user commits the word with space/send.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Ramadhan Sjamsani
75343f97b6