refactor: move KV repositories to infrastructure (Track P — points 2, 6c)

Make the domain stop depending on infrastructure ("imports point inward").

- Point 2: relocate the four KV adapters (FeedRepository, IconRepository,
  WebSubSubscriptionRepository, CountersRepository) from domain/ to
  infrastructure/, where the logger import is legitimate. The domain now keeps
  only the pure key schema (feed-keys.ts), the Feed aggregate and value objects;
  it imports nothing outward. Deliberately no hand-rolled 24-method port
  interface (YAGNI without DI) — relocation alone fixes the direction.
- Point 6c: EmailParser.extractFeedId now returns a validated FeedId value
  object instead of a raw string, so the most untrusted input (an inbound
  recipient address) is guarded at the parse boundary and no longer round-trips
  through FeedId.fromTrusted in the ingest path.

All import paths updated; CLAUDE.md source layout/KV-schema notes updated.
351 tests pass; tsc --noEmit clean.

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

src/routes/admin/emails.tsx

@@ -6,7 +6,7 @@ import {
   deleteAttachmentsForEmails,
   deleteKeysWithConcurrency,
 } from "./helpers";
-import { FeedRepository } from "../../domain/feed-repository";
+import { FeedRepository } from "../../infrastructure/feed-repository";
 import { FeedId } from "../../domain/value-objects/feed-id";
 import {
   feedRssUrl,

src/routes/admin/feeds.tsx

@@ -9,7 +9,7 @@ import { sendUnsubscribes } from "../../infrastructure/unsubscribe";
 import { getAttachmentBucket } from "../../infrastructure/attachments";
 import { Layout } from "./ui";
 import { purgeFeedKeysStep, collectUnsubscribeUrls } from "./helpers";
-import { FeedRepository } from "../../domain/feed-repository";
+import { FeedRepository } from "../../infrastructure/feed-repository";
 import { FeedId } from "../../domain/value-objects/feed-id";
 import {
   createFeedRecord,

src/routes/admin/helpers.ts

@@ -1,7 +1,7 @@
 import { EmailData, EmailMetadata, Env } from "../../types";
 import { logger } from "../../infrastructure/logger";
 import { getAttachmentBucket } from "../../infrastructure/attachments";
-import { FeedRepository } from "../../domain/feed-repository";
+import { FeedRepository } from "../../infrastructure/feed-repository";
 import { FeedId } from "../../domain/value-objects/feed-id";
 
 // Delete the R2 attachments belonging to the given email keys. Call before the