Chore: Restructure Repository for SvelteKit

_old/core/theme.ts

@@ -0,0 +1,67 @@
+import { store, updateSettings } from "@store/state.svelte";
+
+let themeStyleEl: HTMLStyleElement | null = null;
+let mediaQuery:   MediaQueryList | null   = null;
+let mediaHandler: (() => void) | null     = null;
+
+export function applyTheme() {
+  const themeId  = store.settings.theme ?? "dark";
+  const isCustom = themeId.startsWith("custom:");
+
+  if (!isCustom) {
+    themeStyleEl?.remove();
+    themeStyleEl = null;
+    document.documentElement.setAttribute("data-theme", themeId);
+    return;
+  }
+
+  const custom = store.settings.customThemes?.find(t => t.id === themeId);
+  if (!custom) {
+    themeStyleEl?.remove();
+    themeStyleEl = null;
+    document.documentElement.setAttribute("data-theme", "dark");
+    return;
+  }
+
+  const vars = Object.entries(custom.tokens)
+    .map(([k, v]) => `  --${k}: ${v};`)
+    .join("\n");
+  const css = `[data-theme="custom"] {\n${vars}\n}`;
+
+  if (!themeStyleEl) {
+    themeStyleEl = document.createElement("style");
+    themeStyleEl.id = "moku-custom-theme";
+    document.head.appendChild(themeStyleEl);
+  }
+  themeStyleEl.textContent = css;
+  document.documentElement.setAttribute("data-theme", "custom");
+}
+
+function applySystemTheme(dark: boolean) {
+  const themeId = dark
+    ? (store.settings.systemThemeDark ?? "dark")
+    : (store.settings.systemThemeLight ?? "light");
+  updateSettings({ theme: themeId });
+}
+
+export function mountSystemThemeSync() {
+  if (mediaQuery && mediaHandler) {
+    mediaQuery.removeEventListener("change", mediaHandler);
+    mediaHandler = null;
+  }
+
+  if (!store.settings.systemThemeSync) return;
+
+  mediaQuery   = window.matchMedia("(prefers-color-scheme: dark)");
+  mediaHandler = () => applySystemTheme(mediaQuery!.matches);
+  mediaQuery.addEventListener("change", mediaHandler);
+  applySystemTheme(mediaQuery.matches);
+}
+
+export function unmountSystemThemeSync() {
+  if (mediaQuery && mediaHandler) {
+    mediaQuery.removeEventListener("change", mediaHandler);
+    mediaHandler = null;
+    mediaQuery   = null;
+  }
+}