[devin-ai-integration]

Summary

theme::install sets TextStyle::Body from settings.text_size, but about 30 text sites in arca-gui/src/ui/ used fixed sizes such as FontId::proportional(14.0) or .size(12.0). That covered browser row names, column headers and cells, peek cards, dialogs, settings rows, the status bar notice and key caps. Because of that, the Text size setting never changed them.

New helpers in theme.rs take the installed Body size and add an offset to it:

text_size(style, delta) -> f32    // Body.size + delta
text_font(style, delta) -> FontId // proportional
mono_font(style, delta) -> FontId // monospace

Each literal now uses one of these with delta = literal - 13 (13 is TEXT_DEFAULT), e.g. FontId::proportional(14.0) → text_font(ui.style(), 1.0). At the default size every font comes out the same as before, so the default look doesn't change.

What stays fixed on purpose: Phosphor icon glyph sizes (icon_font(..)/icon_text(..).size(..)), the stepper's −/+ signs, and the test fixtures in highlight.rs. They sit inside fixed geometry (24/30 px rows, a 26 px text offset after the row glyph, fixed button sizes). Scaling them would mean reworking that layout, which this PR doesn't do.

Tests: added view_text_follows_the_text_size_setting (theme.rs). It runs install at the default size and at 18 pt for both themes and checks the derived sizes. cargo clippy -p arca-gui --all-targets -D warnings and cargo test -p arca-gui pass. I also ran it by hand at text_size = 20: 21 px row names still fit in the Compact 24 px rows.

Link to Devin session: https://app.devin.ai/sessions/0f38f47b919e4d97a58d909cf30be015
Open in Devin Desktop: https://app.devin.ai/desktop/session/0f38f47b919e4d97a58d909cf30be015?variant=devin
Requested by: @Villoh

[devin-ai-integration]

I'll fix CI failures and address comments from users with write access. I'll skip comments containing "(aside)".

• Disable automatic comment, CI, and merge conflict monitoring