feat: bookmarks for notes and articles (NIP-51) (#29)

* feat: bookmarks for notes and articles (NIP-51)

Adds a Bookmarks app backed by a kind 10003 NIP-51 bookmark list:
- BookmarkButton toggles a note (`e` tag) or article (`a` tag) in and
  out of the signed-in user's list, reading it back before publishing
  so an update never clobbers other entries — the same whole-list
  replacement trap follow lists have.
- Wired into NoteCard's action row and the Reader's article toolbar.
- The new Bookmarks app lists saved notes and articles, opening
  articles back in the Reader.

Closes #21

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BYiUtZMQeA5RHggQw73wto

* fix: address review feedback and add a Bookmarked tab to the Reader

Per review:
- useToggleBookmark now fetches the bookmark list fresh from relays
  right before writing instead of trusting the query cache (60s
  staleTime), which could otherwise clobber concurrent edits from
  another tab or device.
- The article BookmarkButton only renders when the article actually
  has a `d` tag, instead of falling back to an unresolvable
  "kind:pubkey:" address.
- Bookmarked note/article ids are filtered for a non-empty tag value
  before use, and article addresses are parsed properly (kind,
  author, `d`) instead of a naive split(':')[2] — the relay query is
  now also constrained by kind and author, not just `d`, and
  identifiers containing ':' round-trip correctly.
- BookmarkButton sets type="button" so it can't misbehave as a form
  submit button.

Per a reviewer comment: added a "Recent" / "Bookmarked" tab to the
Reader's sidebar (src/apps/articles/index.tsx) so bookmarked articles
are reachable without leaving the app — the dedicated Bookmarks app
stays as-is. Both now share useMyBookmarkedArticles from
src/hooks/useBookmarks.ts rather than duplicating the address-parsing
logic.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BYiUtZMQeA5RHggQw73wto

* fix: reject empty-identifier addresses and surface bookmark load errors

Per review:
- parseAddress() now rejects an empty d-identifier as malformed
  (e.g. "30023:<pubkey>:") instead of producing a "#d: ['']" relay
  query and an unopenable bookmark.
- useMyBookmarkedArticles() filters out matched events with empty
  content, the same non-renderable criteria the Reader's own list
  uses, so a broken/blank article can't land in the Bookmarked view.
- BookmarksApp now distinguishes "the query failed" from "there are
  no bookmarks" — React Query leaves data undefined in both cases, so
  a relay/network failure no longer reads as an empty list.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BYiUtZMQeA5RHggQw73wto

---------

Co-authored-by: highperfocused <highperfocused@pm.me>
Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>

docs/apps.md

@@ -89,7 +89,7 @@ export default function ExampleApp({ setTitle }: AppProps) {
 }
 ```
 
-## The seven apps
+## The eight apps
 
 | App | `id` | Params | Notes |
 |---|---|---|---|
@@ -97,10 +97,17 @@ export default function ExampleApp({ setTitle }: AppProps) {
 | Profile | `profile` | `pubkey`, `relays?` | kind 0 metadata, the author's notes, follow/unfollow |
 | Note | `notes` | `id?`, `relays?` | One note and its replies, or a blank local draft when `id` is absent. **Not** a singleton |
 | Reader | `articles` | `pubkey?`, `identifier?`, `kind?`, `relays?` | NIP-23 long-form, `react-markdown` |
+| Bookmarks | `bookmarks` | — | NIP-51 kind 10003 list — bookmarked notes and articles |
 | Relays | `relays` | — | Connection state, subscription count, measured latency |
 | Settings | `settings` | — | Theme, relay list, Blossom servers, account, session |
 | About | `about` | — | What this is, the app list, the shortcuts |
 
+### Bookmarks are one whole-list replacement, like follow lists
+
+kind 10003 is a replaceable event: publishing it replaces the entire list. `useToggleBookmark`
+(`src/hooks/useBookmarks.ts`) therefore reads the current list back before publishing an
+update, the same trap [follow lists](#follow-lists-are-a-whole-list-replacement) have.
+
 ### Follow lists are a whole-list replacement
 
 kind 3 replaces the entire contact list. The follow button therefore reads the current