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

demos/postgres/src/utils/reading-time.ts

@@ -0,0 +1,66 @@
+import type { PortableTextBlock } from "emdash";
+
+const WORDS_PER_MINUTE = 200;
+const CJK_CHARACTERS_PER_MINUTE = 500;
+const WHITESPACE_REGEX = /\s+/;
+const CJK_CHARACTER_REGEX =
+	/\p{Script=Han}|\p{Script=Hangul}|\p{Script=Hiragana}|\p{Script=Katakana}/gu;
+
+type PortableTextSpan = {
+	_type: string;
+	text?: string;
+};
+
+type PortableTextTextBlock = PortableTextBlock & {
+	_type: "block";
+	children: PortableTextSpan[];
+};
+
+function isTextBlock(block: PortableTextBlock): block is PortableTextTextBlock {
+	return block._type === "block" && Array.isArray(block.children);
+}
+
+function countWords(text: string): number {
+	return text.split(WHITESPACE_REGEX).filter(Boolean).length;
+}
+
+function countCjkCharacters(text: string): number {
+	return text.match(CJK_CHARACTER_REGEX)?.length ?? 0;
+}
+
+/**
+ * Extract plain text from Portable Text blocks
+ */
+export function extractText(blocks: PortableTextBlock[] | undefined): string {
+	if (!blocks || !Array.isArray(blocks)) return "";
+
+	return blocks
+		.filter(isTextBlock)
+		.map((block) =>
+			block.children
+				.filter((child) => child._type === "span" && typeof child.text === "string")
+				.map((span) => span.text)
+				.join(""),
+		)
+		.join(" ");
+}
+
+/**
+ * Calculate reading time in minutes from Portable Text content
+ */
+export function getReadingTime(content: PortableTextBlock[] | undefined): number {
+	const text = extractText(content);
+	const cjkCharacterCount = countCjkCharacters(text);
+	const wordCount = countWords(text.replace(CJK_CHARACTER_REGEX, " "));
+	const minutes = Math.ceil(
+		wordCount / WORDS_PER_MINUTE + cjkCharacterCount / CJK_CHARACTERS_PER_MINUTE,
+	);
+	return Math.max(1, minutes);
+}
+
+/**
+ * Format reading time for display
+ */
+export function formatReadingTime(minutes: number): string {
+	return `${minutes} min read`;
+}