Fixed problem with Content security policy

* Modernize UI with dark theme, sidebar layout, and mobile responsiveness

- Introduce a full CSS design-token system (colors, radii, shadows, fonts)
- Replace the flat top-bar with a fixed sidebar (logo, nav, avatar, sign-out)
- Add a mobile top-bar + slide-in sidebar with hamburger toggle
- Redesign login page as a centered full-screen card
- Restyle entry list with card rows, monogram avatars, and client-side search
- Restyle Create/Edit forms with card containers, icon buttons, and field hints
- Restyle Details view with a split header/body card and monospaced secret block
- Ensure full mobile responsiveness at 768 px and 480 px breakpoints

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Fix IndexOutOfRangeException when entry title is empty

Guard against empty Title strings in the entry list icon display to
prevent crashes when accessing the first character.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* Move inline search script to external file to satisfy CSP

Inline scripts are blocked by the production Content Security Policy.
Extracted the entry search logic into wwwroot/js/entries-search.js
and replaced the inline <script> block with an external reference.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: mzagozda

wwwroot/js/entries-search.js

@@ -0,0 +1,11 @@
+(function () {
+    var input = document.getElementById('searchInput');
+    if (!input) return;
+    input.addEventListener('input', function () {
+        var q = this.value.toLowerCase();
+        document.querySelectorAll('#entryList li').forEach(function (li) {
+            var item = li.querySelector('.entry-item');
+            li.style.display = (!q || item.dataset.title.includes(q)) ? '' : 'none';
+        });
+    });
+})();