Added a dialog with each opportunity's details and releases

Every row has a details icon under the Find a Tender link. It opens a
dialog with the opportunity's details from the list, and fetches the
opportunity with its releases, shown as tabs, newest first. Each tab
summarises the release's tender, awards and contracts, links to its
Find a Tender notice where it is one, and has the release's JSON,
pretty-printed and highlighted, in a section laid out only when it's
opened.

The JSON is highlighted by splitting it into tokens shown as text, not
HTML, as releases come from outside sources. The README's saved
preferences now include the filters.

web/src/lib/format.ts

@@ -8,6 +8,14 @@ const dateFormat = new Intl.DateTimeFormat('en-GB', {
   year: 'numeric',
 });
 
+const dateTimeFormat = new Intl.DateTimeFormat('en-GB', {
+  day: 'numeric',
+  month: 'short',
+  year: 'numeric',
+  hour: '2-digit',
+  minute: '2-digit',
+});
+
 const moneyFormat = new Intl.NumberFormat('en-GB', {
   style: 'currency',
   currency: 'GBP',
@@ -29,6 +37,12 @@ export function formatDate(value: DateTimeString | null | undefined): string {
   return d ? dateFormat.format(d) : '—';
 }
 
+/** A date and time for display, e.g. "3 Mar 2026, 09:30", or a dash for none. */
+export function formatDateTime(value: DateTimeString | null | undefined): string {
+  const d = parseDate(value);
+  return d ? dateTimeFormat.format(d) : '—';
+}
+
 /** An amount in pounds for display, e.g. "£125,001", or a dash for none. */
 export function formatMoney(value: number): string {
   return value > 0 ? moneyFormat.format(value) : '—';
@@ -38,3 +52,21 @@ export function formatMoney(value: number): string {
 export function formatCount(value: number): string {
   return countFormat.format(value);
 }
+
+/**
+ * An amount in its currency for display, e.g. "€1,201", or a dash for none.
+ * A currency code Intl doesn't know is shown after the number.
+ */
+export function formatValue(amount: number, currency: string): string {
+  if (amount <= 0) return '—';
+  if (currency === '' || currency === 'GBP') return moneyFormat.format(amount);
+  try {
+    return new Intl.NumberFormat('en-GB', {
+      style: 'currency',
+      currency,
+      maximumFractionDigits: 0,
+    }).format(amount);
+  } catch {
+    return `${countFormat.format(Math.round(amount))} ${currency}`;
+  }
+}