Rewrite domain objects as a Reader/Builder split

Replace the single DomainObject/EncryptableList classes with a read/write split
that removes the optional-event ambiguity:

- base.ts: EventReader<P> (static kind; fromEvent(event, signer?) eagerly computes
  a generic `plain`, validates leniently, throws-or-passes; lazy method accessors;
  group/protect/expires + extraTags carry-over; builder()) and EventBuilder<P>
  (chainable setters, buildTags/buildContent, validate-on-emit).
- List.ts: ListReader/ListBuilder for NIP-51 lists (decrypt-on-read into `plain`,
  re-encrypt-on-emit, tag mutators).
- Every kind converted to a <Noun> reader + <Noun>Builder pair; membership ops
  split into per-kind reader/builder pairs over a shared abstract base.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01V67tPYdvh1qCkjEBhJGZUR

packages/domain/src/BookmarkList.ts

@@ -6,13 +6,13 @@ import {
   getTopicTagValues,
   getTagValues,
 } from "@welshman/util"
-import {EncryptableList} from "./List.js"
+import {ListReader, ListBuilder} from "./List.js"
 
 // NIP-51 kind-10003 bookmark list. Mixed entries (notes via 'e', articles via
 // 'a', hashtags via 't', urls via 'r') can be bookmarked publicly (tags) or
 // privately (encrypted content); accessors treat both as one merged set.
-export class BookmarkList extends EncryptableList {
-  readonly kind = BOOKMARKS
+export class BookmarkList extends ListReader {
+  static kind = BOOKMARKS
 
   ids() {
     return uniq(getEventTagValues(this.tags()))
@@ -30,6 +30,14 @@ export class BookmarkList extends EncryptableList {
     return uniq(getTagValues("r", this.tags()))
   }
 
+  builder() {
+    return this.seedList(new BookmarkListBuilder())
+  }
+}
+
+export class BookmarkListBuilder extends ListBuilder {
+  static kind = BOOKMARKS
+
   bookmarkPublicly(tag: string[]) {
     return this.addPublicTags(tag)
   }