fix(assets,theme): remove assert in svg_loader, log theme failures, fix default theme id (#58, #63, #64)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

solitaire_engine/src/theme/registry.rs

@@ -21,11 +21,12 @@
 
 use std::path::Path;
 
+use bevy::log::warn;
 use bevy::prelude::{App, Plugin, Resource, Startup};
 use serde::Deserialize;
 
 use super::ThemeMeta;
-use crate::assets::{user_theme_dir, DARK_THEME_MANIFEST_URL};
+use crate::assets::{DARK_THEME_MANIFEST_URL, user_theme_dir};
 
 /// One entry in the [`ThemeRegistry`] — the data the picker UI needs
 /// to render a row and load the theme on selection.
@@ -143,7 +144,7 @@ fn classic_entry() -> ThemeEntry {
 /// Walks `user_dir`, treating every immediate subdirectory as a
 /// candidate theme. A subdirectory contributes one entry if and only
 /// if it contains a `theme.ron` whose `meta` block parses cleanly and
-/// passes `ThemeMeta::validate`. Failed candidates are silently
+/// passes `ThemeMeta::validate`. Failed candidates are warned and
 /// skipped — broken themes don't poison discovery.
 fn discover_user_themes(user_dir: &Path) -> Vec<ThemeEntry> {
     let mut out = Vec::new();
@@ -184,9 +185,29 @@ struct ManifestMetaOnly {
 /// [`ThemeEntry`]. Returns `None` for any I/O / parse / validation
 /// failure — discovery is best-effort.
 fn read_meta_only(manifest_path: &Path) -> Option<ThemeEntry> {
-    let bytes = std::fs::read(manifest_path).ok()?;
-    let parsed: ManifestMetaOnly = ron::de::from_bytes(&bytes).ok()?;
-    parsed.meta.validate().ok()?;
+    let theme_id = manifest_path
+        .parent()
+        .and_then(Path::file_name)
+        .and_then(|name| name.to_str())
+        .unwrap_or("<unknown>");
+    let bytes = match std::fs::read(manifest_path) {
+        Ok(bytes) => bytes,
+        Err(e) => {
+            warn!("Skipping theme '{}': {}", theme_id, e);
+            return None;
+        }
+    };
+    let parsed: ManifestMetaOnly = match ron::de::from_bytes(&bytes) {
+        Ok(parsed) => parsed,
+        Err(e) => {
+            warn!("Skipping theme '{}': {}", theme_id, e);
+            return None;
+        }
+    };
+    if let Err(e) = parsed.meta.validate() {
+        warn!("Skipping theme '{}': {}", theme_id, e);
+        return None;
+    }
     let id = parsed.meta.id.clone();
     let display_name = parsed.meta.name.clone();
     let manifest_url = format!("themes://{id}/theme.ron");