Expand ecash explorer capabilities

Add Fedimint discovery, dual SQLite/Postgres storage, richer review handling, and generated social imagery.

web/src/lib/seo.ts

@@ -90,3 +90,46 @@ export function clampWords(value: string, max: number): string {
   const lastSpace = cut.lastIndexOf(' ');
   return (lastSpace > max * 0.6 ? cut.slice(0, lastSpace) : cut).trimEnd();
 }
+
+/**
+ * A mint's own description, made fit to open a meta description.
+ *
+ * It is operator-written text headed for a `content` attribute and a link preview, so
+ * everything that does not belong in either comes out: HTML tags and control
+ * characters are stripped, whitespace collapses, and only the first sentence
+ * survives — a meta description quoting three sentences of marketing leaves no room
+ * for the rating and status that make the snippet useful. (Astro does the actual
+ * attribute escaping; this removes what escaping would merely neutralise.)
+ *
+ * Two judgement calls:
+ *
+ *   - SHOUTING is normalised to sentence case. A description that is ≥80% capitals
+ *     reads as noise in a search result, and the mint's page still shows the original.
+ *   - The sentence split requires whitespace after the terminator, so "mint.example.com"
+ *     inside a sentence does not end it.
+ *
+ * Returns null when nothing usable is left, and the caller falls back to its own copy.
+ */
+export function cleanMintDescription(value: string | null | undefined, max = 70): string | null {
+  if (!value) return null;
+
+  let clean = value
+    .replace(/<[^>]*>/g, ' ')
+    .replace(/[\u0000-\u001f\u007f-\u009f]/g, ' ')
+    .replace(/\s+/g, ' ')
+    .trim();
+  if (clean === '') return null;
+
+  const sentence = /^.*?[.!?](?=\s|$)/.exec(clean);
+  clean = (sentence?.[0] ?? clean).trim();
+
+  const letters = clean.replace(/[^\p{L}]/gu, '');
+  if (letters.length >= 8 && letters.replace(/\p{Ll}/gu, '').length / letters.length > 0.8) {
+    clean = clean.toLowerCase();
+    clean = clean[0]!.toUpperCase() + clean.slice(1);
+  }
+
+  clean = clampWords(clean, max);
+  if (!/[.!?]$/.test(clean)) clean += '.';
+  return clean;
+}