style(theme): expand color palettes and refine dark mode styles

- Expand CSS variables for primary and secondary colors to include full 50-950 scales in `main.css`.
- Update components to reference specific color shades (e.g., `primary-400`, `secondary-200`) instead of generic variables.
- Add dark mode background and text colors to Events, Hall of Fame, and Index sections.
- Adjust image aspect ratio in the Events component.

app/pages/about/founded-history.vue

@@ -131,7 +131,7 @@
                   :class="[
                     'px-4',
                     'py-2',
-                    idx < 2 ? 'font-bold text-primary' : '',
+                    idx < 2 ? 'font-bold text-primary-400' : '',
                   ]"
                 >
                   {{ donor.amount }}
@@ -167,7 +167,7 @@
                   {{ money.format(serviceDonor.amount) }}
                 </td>
               </tr>
-              <tr class="bg-amber-50 font-semibold text-primary">
+              <tr class="bg-amber-50 font-semibold text-primary-400">
                 <td class="px-4 py-2">总额</td>
                 <td class="px-4 py-2">专业服务及装修项目</td>
                 <td class="px-4 py-2">{{ money.format(33170) }}</td>