fix(fc3b): SourceFormDialog + SubscriptionsView read platforms store; drop sources.loadPlatforms

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/components/subscriptions/SourceFormDialog.vue

@@ -20,7 +20,13 @@
           Adding source for <strong>{{ initialArtist.name }}</strong>
         </div>
 
-        <v-select v-model="platform" :items="store.platforms" label="Platform" />
+        <v-select
+          v-model="platform"
+          :items="platformsItems"
+          item-value="value"
+          item-title="title"
+          label="Platform"
+        />
         <v-text-field v-model="url" label="URL" :error-messages="urlError" />
         <v-switch v-model="enabled" label="Enabled" color="accent" hide-details />
 
@@ -65,6 +71,7 @@
 <script setup>
 import { computed, ref, watch } from 'vue'
 import { useSourcesStore } from '../../stores/sources.js'
+import { usePlatformsStore } from '../../stores/platforms.js'
 
 const props = defineProps({
   modelValue: { type: Boolean, default: false },
@@ -73,6 +80,11 @@ const props = defineProps({
 })
 const emit = defineEmits(['update:modelValue', 'saved'])
 const store = useSourcesStore()
+const platformsStore = usePlatformsStore()
+
+const platformsItems = computed(() =>
+  platformsStore.list.map(p => ({ value: p.key, title: p.name }))
+)
 
 const artistChoice = ref(null)
 const artistMatches = ref([])
@@ -128,7 +140,7 @@ const canSave = computed(() => !jsonError.value && !!url.value.trim())
 watch(() => props.modelValue, async (open) => {
   if (!open) return
   urlError.value = ''; jsonError.value = ''
-  await store.loadPlatforms()
+  await platformsStore.loadAll()
   if (props.source) {
     platform.value = props.source.platform
     url.value = props.source.url
@@ -139,7 +151,7 @@ watch(() => props.modelValue, async (open) => {
     jsonText.value = JSON.stringify(co, null, 2)
     artistChoice.value = { id: props.source.artist_id, name: props.source.artist_name }
   } else {
-    platform.value = store.platforms[0] || 'patreon'
+    platform.value = platformsStore.list[0]?.key || 'patreon'
     url.value = ''; enabled.value = true
     structuredVideos.value = true; structuredSince.value = ''
     jsonText.value = '{}'