feat: add support for multi-themes (#210)

* chore: update deps

* wip

* add themes

* add matrix theme

* add flexoki and spaceduck themes

* .

* simple theme change function

* .

* respect shadow and radius settings

* add rose pine themes

* toggle theme

crates/theme/src/registry.rs

@@ -0,0 +1,70 @@
+use std::collections::HashMap;
+use std::rc::Rc;
+use std::sync::Arc;
+
+use anyhow::{Context as AnyhowContext, Error};
+use gpui::{App, AppContext, AssetSource, Context, Entity, Global, SharedString};
+
+use crate::ThemeFamily;
+
+pub fn init(cx: &mut App) {
+    ThemeRegistry::set_global(cx.new(ThemeRegistry::new), cx);
+}
+
+struct GlobalThemeRegistry(Entity<ThemeRegistry>);
+
+impl Global for GlobalThemeRegistry {}
+
+pub struct ThemeRegistry {
+    /// Map of theme names to theme families
+    themes: HashMap<SharedString, Rc<ThemeFamily>>,
+}
+
+impl ThemeRegistry {
+    /// Retrieve the global theme registry state
+    pub fn global(cx: &App) -> Entity<Self> {
+        cx.global::<GlobalThemeRegistry>().0.clone()
+    }
+
+    /// Set the global theme registry instance
+    pub(crate) fn set_global(state: Entity<Self>, cx: &mut App) {
+        cx.set_global(GlobalThemeRegistry(state));
+    }
+
+    /// Create a new theme registry instance
+    pub(crate) fn new(cx: &mut Context<Self>) -> Self {
+        let mut themes = HashMap::new();
+        let asset = cx.asset_source();
+
+        if let Ok(paths) = asset.list("themes") {
+            for path in paths.into_iter() {
+                match Self::load(&path, asset) {
+                    Ok(theme) => {
+                        themes.insert(path, Rc::new(theme));
+                    }
+                    Err(e) => {
+                        log::error!("Failed to load theme: {path}. Error: {e}");
+                    }
+                }
+            }
+        }
+
+        Self { themes }
+    }
+
+    /// Load a theme from the asset source.
+    fn load(path: &str, asset: &Arc<dyn AssetSource>) -> Result<ThemeFamily, Error> {
+        // Load the theme file from the assets
+        let content = asset.load(path)?.context("Theme not found")?;
+
+        // Parse the JSON content into a Theme Family struct
+        let theme: ThemeFamily = serde_json::from_slice(&content)?;
+
+        Ok(theme)
+    }
+
+    /// Returns a reference to the map of themes.
+    pub fn themes(&self) -> &HashMap<SharedString, Rc<ThemeFamily>> {
+        &self.themes
+    }
+}