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/manifest/src/tests.rs

@@ -167,6 +167,8 @@ fn only_the_subset_parses() {
         "id = kos.snake",       // bare value
         "id \"kos.snake\"",     // no =
         "[app",                 // unclosed table
+        "id = 12x",             // not a whole number
+        "id = 1.5",             // no fractions
     ] {
         assert!(
             matches!(