Add crates/qbz-theme/src/custom.rs: the extended port of the Tauri "edit
theme colors" feature. A CustomThemeBase of 12 hand-picked semantic tokens
(surfaces, text, accent, status hues, border, favorite + is_dark polarity),
stored as opaque #rrggbb hex strings, derives the full ThemeColors contract.
Unlike Tauri (8 raw vars, no derivation, over the auto-theme only), editing a
base token now cascades: theme_from_base derives the accent triplet
(+0.10/-0.10 lightness, contrast-picked accent_text), the danger/warning/
success families (0.1/0.3 tints, polarity hover), muted/disabled text tiers,
border_strong, the translucent edges and the polarity alpha ramp.
Reuses the existing math instead of duplicating it: generator::{tint,
pick_btn_text_for_accent_set, ensure_text_contrast_target} are now pub(crate);
PaletteColor::shift_lightness and alpha_ramp are shared as-is. base_from_theme
is the inverse seed ("Start from current theme") and round-trips exactly for
any theme this module authored. Adds Rgba::to_hex. 9 unit tests (roundtrip,
polarity, determinism, accent-text legibility, malformed-hex fallback, JSON).
cc
Port the legacy Tauri src-tauri/src/auto_theme/{palette,system,generator}
logic into a new frontend-agnostic qbz-theme::auto module. The palette
extraction (k-means), WCAG contrast math, HSL shifts and DE detection are
carried over 1:1; only the final assembly changes: the output is now the
registry ThemeColors contract instead of a CSS custom-property map.
The generator mirrors registry::StdSpec::build so a generated theme
composites identically to a static one — same polarity-driven alpha ramp,
success/focus_ring/favorite/border_muted derivations, and status tints.
Per-status text tokens (--btn-danger-text/--btn-warning-text) are dropped
since ThemeColors has no field for them.
Adds `image` (0.25, minimal codec features) to qbz-theme and unit tests for
the mapping (polarity, derived families, determinism, scheme path).
cc
Introduce the `qbz-theme` crate (ADR-006): pure Rust, no Slint/Tauri/heavy
deps, hand-rolled color + contrast math. It holds the scalable theming data
model the Slint migration consumes.
- `Rgba` + WCAG relative-luminance/contrast-ratio + an APCA Lc approximation
(secondary a11y gate for P3 tests).
- `ThemeColors`: the complete token contract (surfaces incl. bg-hover, text,
accent, danger/warning/success families, border-subtle/muted/strong,
focus-ring, favorite, card-shadow, 24-tier alpha superset with polarity
baked in).
- `ThemeId` enum (all 33 themes) with stable slugs, display names (proper-noun
data, not i18n keys), Core/Dark/Light/Accessibility categories, and a
luminance-derived light/dark flag. `default_theme_id()` = OLED.
- Registry materializes the 4 P1 themes (Dark/OLED/Tokyo Night/System-fallback)
from src/app.css, preserving the legacy translucent alias values so the
existing themes stay pixel-identical; derives the new token families.
- 22 unit tests (registry fully populated, default is OLED, legacy alpha
aliases unchanged, slug roundtrip).
cc
vicrodh