Fixes #5: Refactor code quality - Part 1

- Split index.js from 1,567 lines to 456 lines (73% reduction)
  - Extracted settings event listeners to src/systems/ui/settingsListeners.js
  - Extracted settings panel to src/core/settingsPanel.js
  - Simplified initUI() and main initialization block

- Modularized style.css into 28 logical CSS modules in src/styles/
  - Added build script (npm run build:css) to concatenate modules
  - Modules: panel, components, user-stats, info-box, thoughts, settings,
    themes, modals, mobile, inventory, quests, equipment, encounters,
    weather, music-player, FAB widgets, strip widgets, etc.

- Updated package.json with build:css script and type: module

No functional changes - pure refactoring for maintainability.

src/styles/_25_import-dialog.css

@@ -0,0 +1,100 @@
+/* ============================================
+   IMPORT MODE DIALOG STYLES
+   ============================================ */
+
+/* Import Mode Dialog Overlay */
+.rpg-import-dialog-overlay {
+    position: fixed;
+    top: 0;
+    left: 0;
+    width: 100%;
+    height: 100%;
+    background: rgba(0, 0, 0, 0.7);
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    z-index: 100000;
+}
+
+.rpg-import-dialog {
+    background: var(--SmartThemeBlurTintColor, #2a2a3e);
+    border: 1px solid var(--SmartThemeBorderColor, #4a4a4a);
+    border-radius: 8px;
+    padding: 20px;
+    min-width: 300px;
+    max-width: 400px;
+    text-align: center;
+    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.5);
+}
+
+.rpg-import-dialog h4 {
+    margin: 0 0 15px 0;
+    color: var(--SmartThemeBodyColor, #eee);
+}
+
+.rpg-import-dialog h4 i {
+    margin-right: 8px;
+    color: var(--SmartThemeQuoteColor, #e94560);
+}
+
+.rpg-import-dialog p {
+    margin: 0 0 20px 0;
+    color: var(--SmartThemeBodyColor, #ccc);
+    font-size: 0.95em;
+}
+
+.rpg-import-dialog-buttons {
+    display: flex;
+    flex-direction: column;
+    gap: 10px;
+    margin-bottom: 15px;
+}
+
+.rpg-import-dialog-buttons button {
+    padding: 10px 15px;
+    border-radius: 6px;
+    cursor: pointer;
+    font-size: 0.95em;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    gap: 8px;
+    transition: all 0.2s ease;
+}
+
+.rpg-import-dialog .rpg-btn-secondary {
+    background: var(--black30a, rgba(0, 0, 0, 0.3));
+    border: 1px solid var(--SmartThemeBorderColor, #4a4a4a);
+    color: var(--SmartThemeBodyColor, #ccc);
+}
+
+.rpg-import-dialog .rpg-btn-secondary:hover {
+    background: var(--SmartThemeBorderColor, #4a4a4a);
+    color: white;
+}
+
+.rpg-import-dialog .rpg-btn-primary {
+    background: var(--SmartThemeQuoteColor, #e94560);
+    border: 1px solid var(--SmartThemeQuoteColor, #e94560);
+    color: white;
+}
+
+.rpg-import-dialog .rpg-btn-primary:hover {
+    background: var(--SmartThemeQuoteColor, #ff5a75);
+    border-color: var(--SmartThemeQuoteColor, #ff5a75);
+}
+
+.rpg-import-dialog .rpg-btn-cancel {
+    background: transparent;
+    border: none;
+    color: var(--SmartThemeBodyColor, #888);
+    cursor: pointer;
+    font-size: 0.85em;
+    padding: 5px;
+}
+
+.rpg-import-dialog .rpg-btn-cancel:hover {
+    color: var(--SmartThemeBodyColor, #ccc);
+    text-decoration: underline;
+}
+