2.1

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>

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