Prep v1.1.0 release: version string, gitignore secrets, docs

- Add VERSION = "1.1.0" to server.py; print at startup, expose via public
  GET /api/config, and show it in the admin header (so deployed == released
  is verifiable at a glance).
- Ignore config.json in .gitignore — it holds the admin password hash and
  session secret; fresh installs use config.json.example.
- README/CLAUDE.md: document the in-app pixel editor (now with shape tools,
  select/move, reference overlay, custom/recent palettes), the receiver health
  dashboard, 9 sprite types, and the asset cache-busting convention.
- Bump admin asset cache-bust to ?v=20260609d.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

admin/admin.js

@@ -28,10 +28,22 @@
         loadConfig();
         loadThemes();
         loadNetworkInfo();
+        loadVersion();
         refreshStatus();
         statusInterval = setInterval(refreshStatus, 5000);
     }
 
+    async function loadVersion() {
+        try {
+            const res = await fetch('/api/config');
+            if (!res.ok) return;
+            const data = await res.json();
+            if (data.version) {
+                document.getElementById('admin-version').textContent = 'v' + data.version;
+            }
+        } catch (e) { /* ignore */ }
+    }
+
     document.getElementById('login-form').addEventListener('submit', async (e) => {
         e.preventDefault();
         const pw = document.getElementById('login-password').value;