refactor: tighten DDD boundaries on the Feed aggregate

Address five modeling tensions in one pass:

- Encapsulation: the Feed aggregate no longer exposes raw config/metadata
  (a shallow Readonly still leaked mutable arrays). It now offers
  intention-revealing accessors that return copies, plus
  toConfigSnapshot/toMetadataSnapshot for the repository and summary() for
  the global registry.
- feeds:list consistency: FeedRepository.save/saveConfig upsert the registry
  entry from feed.summary(), so services no longer mirror title/description/
  expiry by hand (the old add/updateInList footgun is gone).
- domain/feed.ts: drop the dead applySenderPolicy, internalise resolveExpiresAt
  and trimToByteBudget into the aggregate; feed.ts keeps only the shared
  isExpired predicate used by the read-model routes.
- Single edit path: remove editDetails; edit(patch, deps) is the sole config
  mutation, with a systematic expired guard. Renaming an expired feed now 403s.
- FeedId flows through the application and infrastructure signatures;
  fromTrusted/parse happen once at the edge, .value only at the serialisation
  boundaries (urls, feed-generator, feed-keys, logs, JSON).

347 tests green, tsc clean, Worker bundle builds.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/routes/rss.ts

@@ -4,6 +4,7 @@ import { generateRssFeed } from "../infrastructure/feed-generator";
 import { fetchFeedData } from "../application/feed-fetcher";
 import { baseUrl, feedRssUrl } from "../infrastructure/urls";
 import { isExpired } from "../domain/feed";
+import { FeedId } from "../domain/value-objects/feed-id";
 
 export async function handle(c: Context<{ Bindings: Env }>): Promise<Response> {
   try {
@@ -12,7 +13,7 @@ export async function handle(c: Context<{ Bindings: Env }>): Promise<Response> {
       return new Response("Feed ID is required", { status: 400 });
     }
 
-    const feedData = await fetchFeedData(feedId, c.env);
+    const feedData = await fetchFeedData(FeedId.fromTrusted(feedId), c.env);
     if (!feedData) {
       return new Response("Feed not found", { status: 404 });
     }