feat(theme): themes as files (theme crate: toml subset + ints, contrast check, wire); whimsy dark + light; display reads themes/, serves THEME/THEME_NAME, init SET_THEME -> THEME_CHANGED to all windows, bar themed; k-ui follows; settings appearance; init keeps choice in sealed users/<id>/settings/, reapplies at sign-in + display restart

crates/theme/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "theme"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+types = { workspace = true }
+manifest = { workspace = true }
+libm = "0.2"