feat(admin): show email count and last-email date per feed

Surface each feed's email count on its Emails button and a "Last email …"
freshness line under the title, in both dashboard views. The values are
projected into feeds:list (kept to a single KV read) via the Feed aggregate,
so toListItemDTO now maps the whole aggregate through its intention-revealing
accessors instead of threading scalar projections. Also fixes long titles
overflowing into the Feed ID column in the table view.

Co-Authored-By: Claude Opus 4.7 <[email protected]>

src/types/index.ts

@@ -111,6 +111,8 @@ export interface FeedListItem {
   expires_at?: number; // Cached from FeedConfig to avoid per-feed KV reads
   pendingConfirmation?: boolean; // Projected from FeedMetadata for the dashboard
   hasNativeFeed?: boolean; // Projected from FeedMetadata for the dashboard pill
+  emailCount?: number; // Projected email index size (dashboard "Emails" count)
+  lastEmailAt?: number; // Projected receivedAt (ms) of the most recent email
 }
 
 // Cumulative monitoring counters (persisted as a KV singleton)