Harden security, modularize API bootstrap, and fix scale SSE auth.

Block web access to sensitive paths, require API_TOKEN for mutations, encrypt GitHub issue credentials in .env, auto-provision tokens for same-origin clients, and pass api_token in scale relay URLs since EventSource cannot send headers.

Co-authored-by: Cursor <cursoragent@cursor.com>

assets/js/core/dom.js

@@ -0,0 +1,11 @@
+/**
+ * EverShelf core — safe HTML escaping (loaded before app.js).
+ */
+function escapeHtml(str) {
+    if (str == null) return '';
+    const div = document.createElement('div');
+    div.textContent = String(str);
+    return div.innerHTML;
+}
+
+window.escapeHtml = escapeHtml;