report a source that is quiet rather than broken, instead of a bare 0

The build log prints a count per source, and CI now declines to fail on
a page that states its own emptiness — which leaves that source showing
an unexplained 0, reading as exactly the fault the gate just decided it
was not. The zero we are content with is the one that has to say why.

It is also the only line that would ever prompt anyone to ask whether a
lane quiet for a month is a game between patches or a wiki that reworded
the sentence a statesNoEvents check is still matching. Nothing else in
the pipeline can tell those apart.

The test count in the layout block was stale at 898 and moves with these
two commits, so it is corrected here.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

test/feed.test.ts

@@ -3,6 +3,7 @@ import {
   brokenSources,
   freshness,
   staleSources,
+  quietSources,
   STALE_AFTER_MS,
   SourceHealth,
 } from "../src/shared/feed.ts";
@@ -175,10 +176,26 @@ describe("telling a broken source from a stale one", () => {
     expect(brokenSources([health({})])).toEqual([]);
   });
 
-  test("a healthy source is neither", () => {
+  test("a healthy source is none of the three", () => {
     const ok = health({ eventCount: 5, parsedCount: 5 });
     expect(brokenSources([ok])).toEqual([]);
     expect(staleSources([ok])).toEqual([]);
+    expect(quietSources([ok])).toEqual([]);
+  });
+
+  test("a source whose page states it lists none is reported as quiet", () => {
+    // Excusing it from the build is not the same as saying nothing about it.
+    // The build log prints a count per source, and an unexplained 0 reads as
+    // the fault this whole distinction exists to deny — so the one empty we
+    // are content with is the one that has to say why.
+    expect(
+      quietSources([health({ parsedCount: 0, statesNoEvents: true })]).map(
+        (s) => s.sourceId,
+      ),
+    ).toEqual(["nikki-fandom-events"]);
+    expect(staleSources([health({ parsedCount: 0, statesNoEvents: true })])).toEqual(
+      [],
+    );
   });
 
   test("a source with nothing current left is reported as stale", () => {