diigo-cache: the public page only reads

/public/<username> reads through the cache's viewer() facet
(PageViewer: stored pages, knownTotal, fill progress — the reader
alone), so it can't fetch from diigo or write storage.

Behavior change, agreed beforehand: an unfetched page no longer fills
itself on a miss; it says "not fetched yet" (JSON: stored: false), and
the owner fills via the webkey page. The HIT/MISS line becomes "stored
<when>". Strangers can no longer make the cache spend the owner's diigo
session; the README's deployment concern shrinks to /api.

Tests: viewing an unfetched page makes no webapp call; the page appears
once stored; fill progress shows after one fill step.

Generated-by: Claude Opus 5.5

diigo-cache/src/cache.ts

@@ -417,6 +417,11 @@ export class PageViewer extends RpcTarget {
 		return stored && { ...stored, cached: true };
 	}
 
+	/** diigo's total, as last stored, or null if nothing is stored */
+	knownTotal(): number | null {
+		return this.#reader.knownTotal();
+	}
+
 	/** the cache's fill job, if any */
 	fillStatus(): Promise<FillStatus | undefined> {
 		return this.#fillStatus();