Add the library, collections, and trash views; theme from style.yaml

The UI gains the views the catalog work was building toward: a windowed
library grid with ratings and flags, the collection tree with drag-to-add,
and trash with restore. derived_sync pushes thumbnail shards and the catalog
snapshot to the server's derived folder.

Tokens now have one source of truth. build.rs reads style.yaml and generates
theme.slint into OUT_DIR, which answers every existing
`import { Theme } from "theme.slint"` unchanged, because Slint resolves
imports against the importing file's directory first and the include paths
after. Generating into OUT_DIR rather than beside the hand-written Slint is
the point: a generated file sitting in ui/ looks exactly like the files
around it that are meant to be edited, and an edit to it would survive until
the next touch of style.yaml — a bug that hides for weeks. build.rs fails
loudly if a stale ui/theme.slint exists, which would otherwise shadow the
generated one silently and make every palette change vanish with no error.

The palette moves to near-neutral dark with achromatic signalling, so the
accent means "modified" or "active" rather than "heading". Shared components
land in widgets.slint: a token that binds several values into one concept is
a component, not a row in a YAML file.

Adds an optional live-style feature that makes the tokens in-out so they can
be written at startup — a feature rather than the default because it stops
the properties being constant-folded.

serde_norway is the YAML crate: serde_yaml and serde_yml are both deprecated,
and its mappings preserve insertion order, which is what lets the generated
Slint keep the token ordering the author chose.

Assisted-by: LLM

ui/dr-ui/Cargo.toml

@@ -19,16 +19,43 @@ dr-plat.workspace = true
 dr-sync.workspace = true
 dr-sync-nextcloud.workspace = true
 dr-pipeline.workspace = true
-slint = { workspace = true, features = ["compat-1-2", "renderer-femtovg", "backend-winit"] }
+dr-catalog.workspace = true
+dr-thumbs.workspace = true
+# The library module writes scan results straight into the catalog, so it
+# needs the same SQLite types dr-catalog exposes.
+rusqlite.workspace = true
+# The renderer is shared, but the backend is not: winit on desktop,
+# android-activity on Android, and enabling both makes the backend selector
+# pick at random. So the backend features live on the target-specific
+# dependencies below rather than here.
+slint = { workspace = true, features = ["compat-1-2", "renderer-femtovg"] }
 wgpu.workspace = true
 anyhow.workspace = true
 log.workspace = true
 pollster.workspace = true
+# Runtime YAML only for `live-style`; release builds read the tokens the
+# Slint compiler folded in at build time and never touch style.yaml.
+serde_norway = { workspace = true, optional = true }
+
+# Backend per platform. Slint already declares its android-activity backend
+# under `cfg(target_os = "android")`, so this only has to name the feature;
+# cargo resolves it away entirely on desktop.
+[target.'cfg(not(target_os = "android"))'.dependencies]
+slint = { workspace = true, features = ["backend-winit"] }
+
+[target.'cfg(target_os = "android")'.dependencies]
+slint = { workspace = true, features = ["backend-android-activity-06"] }
 
 [build-dependencies]
 slint-build.workspace = true
+# build.rs generates theme.slint from style.yaml (S2).
+serde_norway.workspace = true
 
 [features]
 default = []
 # Temporary CPU readback path; see dr-ui docs and spike S1.
 readback = ["dr-gpu/readback"]
+# Debug convenience: re-read style.yaml at startup so a palette can be tuned
+# without rebuilding. Costs the constant-folding of every token, so it stays
+# off by default and has no business in a release build.
+live-style = ["dep:serde_norway"]