Emdash source with visual editor image upload fix

Fixes:
1. media.ts: wrap placeholder generation in try-catch
2. toolbar.ts: check r.ok, display error message in popover

packages/core/tests/unit/templates/blog-reading-time.test.ts

@@ -0,0 +1,26 @@
+import { describe, expect, it } from "vitest";
+
+import { getReadingTime } from "../../../../../templates/blog/src/utils/reading-time";
+
+function makeContent(text: string) {
+	return [
+		{
+			_type: "block",
+			children: [{ _type: "span", text }],
+		},
+	];
+}
+
+describe("blog template reading time", () => {
+	it("keeps word-based reading time for English content", () => {
+		expect(getReadingTime(makeContent("word ".repeat(200)))).toBe(1);
+	});
+
+	it("counts CJK content by character length", () => {
+		expect(getReadingTime(makeContent("日".repeat(2000)))).toBe(4);
+	});
+
+	it("adds English words and CJK characters for mixed-language posts", () => {
+		expect(getReadingTime(makeContent(`${"word ".repeat(100)}${"日".repeat(500)}`))).toBe(2);
+	});
+});