Make a stored id always name a row

Review found the new settings row opening nothing for a rule whose `until`
precedes its `startsAt`. That parses — nothing ties the two together — and
yields no occurrence at all, so nextOccurrences and the anchor fallback both
come back empty, nearestOccurrence returns null, and openRow cannot resolve
a bare rule id. It was the undeletable record this index exists to rescue,
now with a button that lies about it.

So resolution moves out of App into displayEventFor, with the rule itself as
the floor: a stored id always names something the reader can edit and
delete, whatever the rule does or does not generate. Exported because
nothing here can click and no test renders App, which is exactly how a dead
button shipped — the chain is now covered without a DOM.

Two of the caption tests could not fail, proven by mutation rather than
read: deleting the whole "starts" branch and removing the null-end guard
both left the suite green, because `not.toContain("ended")` was never
watching the branch at risk. They assert what the caption says now.

And a repeating series that has stopped said only how often it repeats — in
the one place whose job is explaining why an event is on no other surface. A
healthy cadence explains nothing; it says when it stopped.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

src/client/components/YourOwn.tsx

@@ -29,7 +29,16 @@ import { cadenceLabel, EventForm, GameForm } from "./CustomForms.tsx";
  */
 export function eventCaption(event: CustomEvent, nowMs: number): string {
   const cadence = cadenceLabel(event.repeat);
-  if (cadence !== null) return cadence;
+  if (cadence !== null) {
+    // A series that has stopped is exactly what this list exists to explain,
+    // and a healthy-looking cadence explains nothing: the reader would see
+    // "on a weekly cycle" and no reason it is missing from the board.
+    const until = event.repeat?.until ?? null;
+    if (until !== null && Date.parse(until) < nowMs) {
+      return `stopped ${formatAbsolute(Date.parse(until), false)}`;
+    }
+    return cadence;
+  }
 
   if (event.endsAt !== null && Date.parse(event.endsAt) < nowMs) {
     return `ended ${formatAbsolute(Date.parse(event.endsAt), false)}`;
@@ -78,7 +87,10 @@ export function YourOwn({
   // An event may be filed under a game we track — a source can miss one — and
   // those have no row above to nest under. Listing them separately is what
   // keeps this index complete: an ended event under Genshin is on no other
-  // surface either, and would be just as stuck.
+  // surface either, and would be just as stuck. It also catches an event whose
+  // own lane has since gone, which `removeGame` refuses to cause but an import
+  // can still deliver — hence "another game" rather than "a game we track",
+  // which would be false for exactly that row.
   const underTracked = Object.values(events).filter(
     (e) => games[e.game] === undefined,
   );
@@ -186,7 +198,7 @@ export function YourOwn({
       {/* Its own heading rather than trailing the list above, which read as
           though these belonged to whichever game happened to be last. */}
       {underTracked.length > 0 && (
-        <p className="mt-4 text-xs text-faint">Filed under a game we track</p>
+        <p className="mt-4 text-xs text-faint">Filed under another game</p>
       )}
       {underTracked.length > 0 && (
         <ul className="mt-1.5 flex flex-col gap-1">