Union conflict at the end of tests/test_core.py -- both branches appended a
test block. Kept both, main's #72/#73 block first. Verified: 265 test
functions = 238 baseline + 15 (#77) + 12 (theming), no duplicates.
BCC has always been dark-only -- BG #1b1d23, hardcoded at import time, with
no light option and no awareness of the desktop's appearance. On a light
desktop it matches nothing else on screen and there was no way to change it.
Adds a Palette value type in bcc_core with DARK (byte-identical to the
colours v1.3.0 shipped) and a new LIGHT, plus resolve_theme(setting,
system_is_dark) so the decision is testable without a Qt app. View > Theme
offers Match system / Light / Dark, persisted in QSettings under ui/theme,
defaulting to following the system.
The light palette's semantic colours are deliberately not the dark ones
lightened: #4ade80 sits near 1.7:1 against white. They are darkened to clear
WCAG AA, and a contrast test enforces >= 4.5:1 for every text colour against
its surface in both palettes so nobody harmonises them back later.
Three near-black literals were baked into the stylesheet (#1a1205 on-accent
text, #202229 disabled table, #16181d diagnostics pane). Fine with one theme,
invisible breakage with two -- each now has a palette slot, and a test
asserts build_stylesheet contains no hex literals at all.
The ~20 inline setStyleSheet(f"color: {MUTED}") call sites are left alone:
apply_palette rebinds the module-level colour names, and an f-string resolves
its names when it runs, so each call site picks up the new colour on its next
render. Switching theme reapplies the global QSS and re-renders the
inline-styled widgets, so nothing is left dark-on-light.
Refs #75