Refactor: Extract inline JS to external files

New JS files:
- auth.js: Password toggle, confirmation validation, copy, regenerate
- generate.js: Form controls, credential display, memory story generation

Updated templates to use external JS:
- login.html, setup.html, account.html
- admin/user_new.html, user_created.html, password_reset.html
- generate.html (now uses generate.js + minimal Jinja-dependent inline)

Core stegasoo.js (943 lines) unchanged - already handles encode/decode

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontends/web/templates/admin/password_reset.html

@@ -46,17 +46,5 @@
 {% endblock %}
 
 {% block scripts %}
-<script>
-function copyField(fieldId) {
-    const field = document.getElementById(fieldId);
-    field.select();
-    document.execCommand('copy');
-
-    // Show brief feedback
-    const btn = field.nextElementSibling;
-    const originalHTML = btn.innerHTML;
-    btn.innerHTML = '<i class="bi bi-check"></i>';
-    setTimeout(() => btn.innerHTML = originalHTML, 1000);
-}
-</script>
+<script src="{{ url_for('static', filename='js/auth.js') }}"></script>
 {% endblock %}