fix: compact todo-item spacing, fix checkbox alignment in detail

Todo items in preview were ~60px tall because marked.js wraps
checkbox-list content in <p> tags, and .prose p adds 0.75em
vertical margin inside the flex item. Three changes:

  - .todo-item p { margin:0; min-height:0 } kills the paragraph
    bloat inside todo rows.
  - Padding 5px→2px, min-height 28→24px, gap 10→8px for tighter
    stacking.
  - align-items switches from center to flex-start with margin-top
    on the checkbox so it sits at the first text line regardless of
    whether the <li> contains a bare text node or a <p>. Fixes the
    upward shift that appeared in the detail preview but not in the
    side panel.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

config.php

@@ -1,7 +1,7 @@
 <?php
 
 define('APP_NAME', 'hyprcrd');
-define('APP_VERSION', '1.9.23');
+define('APP_VERSION', '1.9.24');
 
 // Database path — writable directory, outside webroot
 // DB_PATH / UPLOAD_DIR can be pre-defined by the Electron router for app isolation