fix(autocomplete): add keyboard navigation and fix scroll/blur in all CODMAT dropdowns

Extract shared setupAutocomplete() into shared.js so all three autocomplete
instances (mappings modal, inline add, quick-map modal) get keyboard nav
(ArrowDown/Up/Enter/Escape), scroll-safe blur handling, and capture-phase
keydown to prevent browser interception. Remove old onmousedown inline
handlers, use data-codmat/data-label attributes instead.

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

api/app/templates/base.html

@@ -169,7 +169,7 @@
 
     <script>window.ROOT_PATH = "{{ rp }}";</script>
     <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/js/bootstrap.bundle.min.js"></script>
-    <script src="{{ rp }}/static/js/shared.js?v=45"></script>
+    <script src="{{ rp }}/static/js/shared.js?v=46"></script>
     <script>
     // Dark mode toggle
     function toggleDarkMode() {

api/app/templates/mappings.html

@@ -159,5 +159,5 @@
 {% endblock %}
 
 {% block scripts %}
-<script src="{{ request.scope.get('root_path', '') }}/static/js/mappings.js?v=14"></script>
+<script src="{{ request.scope.get('root_path', '') }}/static/js/mappings.js?v=17"></script>
 {% endblock %}