Replace themes (Sepia, Nord Frost), batch bookmark fetch, debounce bookmark publish

- Replace Solarized (low contrast) with Sepia (warm coffee tones)
- Replace Tokyo Night with Nord Frost (cool blue-grey, brighter)
- Bookmark fetch uses single batch filter instead of one-by-one (much faster)
- Debounce bookmark publish to prevent race conditions with replaceable events

src/lib/themes.ts

@@ -83,23 +83,23 @@ export const themes: Theme[] = [
     },
   },
   {
-    id: "tokyo-night",
-    name: "Tokyo Night",
+    id: "sepia",
+    name: "Sepia",
     colors: {
-      bg: "#1a1b26",
-      "bg-raised": "#24283b",
-      "bg-hover": "#292e42",
-      border: "#3b4261",
-      "border-subtle": "#292e42",
-      text: "#a9b1d6",
-      "text-muted": "#565f89",
-      "text-dim": "#3b4261",
-      accent: "#7aa2f7",
-      "accent-hover": "#89b4fa",
-      zap: "#e0af68",
-      danger: "#f7768e",
-      warning: "#e0af68",
-      success: "#9ece6a",
+      bg: "#2b2018",
+      "bg-raised": "#382a1f",
+      "bg-hover": "#453527",
+      border: "#5a4636",
+      "border-subtle": "#382a1f",
+      text: "#e8d5c4",
+      "text-muted": "#b89c84",
+      "text-dim": "#7a6452",
+      accent: "#e09850",
+      "accent-hover": "#c47f3a",
+      zap: "#f0c040",
+      danger: "#d45040",
+      warning: "#e0a040",
+      success: "#7ab860",
     },
   },
   {
@@ -123,23 +123,23 @@ export const themes: Theme[] = [
     },
   },
   {
-    id: "ethereal",
-    name: "Ethereal",
+    id: "nord",
+    name: "Nord Frost",
     colors: {
-      bg: "#1a1a2e",
-      "bg-raised": "#16213e",
-      "bg-hover": "#1f2f50",
-      border: "#2a3a5c",
-      "border-subtle": "#1f2f50",
-      text: "#dfe6e9",
-      "text-muted": "#a0aec0",
-      "text-dim": "#5a6a8a",
-      accent: "#a29bfe",
-      "accent-hover": "#6c5ce7",
-      zap: "#ffeaa7",
-      danger: "#ff7675",
-      warning: "#ffeaa7",
-      success: "#55efc4",
+      bg: "#2e3440",
+      "bg-raised": "#3b4252",
+      "bg-hover": "#434c5e",
+      border: "#4c566a",
+      "border-subtle": "#3b4252",
+      text: "#eceff4",
+      "text-muted": "#d8dee9",
+      "text-dim": "#7b88a1",
+      accent: "#88c0d0",
+      "accent-hover": "#81a1c1",
+      zap: "#ebcb8b",
+      danger: "#bf616a",
+      warning: "#ebcb8b",
+      success: "#a3be8c",
     },
   },
   {