feat: add TodoMVC example with editorial design

Full TodoMVC implementation using Pocketbook's synced atom:
- Add, toggle, edit (double-click), destroy todos
- Filter: All / Active / Completed
- Toggle all, clear completed
- Live sync status indicator (online/offline/pending)
- Data persists in IndexedDB, syncs to server via Transit

Design: Ink & Paper aesthetic — cream paper background with grain
texture, Instrument Serif italic header, Newsreader body text,
DM Mono UI chrome, terracotta accent with green completion marks,
deckled left border on card.

Also:
- Server now serves static files from resources/public (/ → todomvc.html)
- Fix CLJS compilation: resolve close!/put! naming conflicts with
  core.async, use qualified async/close!, add clojure.string require
- Fix unbalanced parens in do-pull!
- Remove old placeholder example

build.edn

@@ -1,4 +1,4 @@
-{:main       pocketbook.example
+{:main       pocketbook.todomvc
  :output-to  "resources/public/js/main.js"
  :output-dir "resources/public/js/out"
  :asset-path "js/out"