feat: add social likes facet to package trends charts

Generalize the download analytics chart into a trends chart that supports both downloads and likes,
extensibly allowing for more facets in the future.

- Add a facet selector (Downloads / Likes) shown on Compare page and in the single-package chart modal
- Add server endpoint and utility for fetching per-package likes evolution from ATProto

Author: serhalp

app/components/Compare/LineChart.vue

@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import DownloadAnalytics from '../Package/DownloadAnalytics.vue'
+import TrendsChart from '../Package/TrendsChart.vue'
 
 const { packages } = defineProps<{
   packages: string[]
@@ -8,6 +8,6 @@ const { packages } = defineProps<{
 
 <template>
   <div class="font-mono">
-    <DownloadAnalytics :package-names="packages" :in-modal="false" />
+    <TrendsChart :package-names="packages" :in-modal="false" show-facet-selector />
   </div>
 </template>

app/components/Package/ChartModal.vue

@@ -1,8 +1,12 @@
-<script setup lang="ts"></script>
+<script setup lang="ts">
+defineProps<{
+  modalTitle?: string
+}>()
+</script>
 
 <template>
   <Modal
-    :modalTitle="$t('package.downloads.modal_title')"
+    :modalTitle="modalTitle ?? $t('package.trends.title')"
     id="chart-modal"
     class="h-full sm:h-min sm:border sm:border-border sm:rounded-lg shadow-xl sm:max-h-[90vh] sm:max-w-3xl"
   >