Sort schedule blocks by start time instead of order_index

Backend queries and model relationship now order by time_start.
Frontend also sorts blocks client-side for reliability across all views.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/stores/schedule.js

@@ -24,9 +24,16 @@ export const useScheduleStore = defineStore('schedule', () => {
     return Math.round((completedBlockIds.value.length / blocks.value.length) * 100)
   })
 
+  function sortBlocksByTime(arr) {
+    return (arr || []).slice().sort((a, b) => {
+      const toMin = (t) => { if (!t) return 0; const [h, m] = t.split(':').map(Number); return h * 60 + m }
+      return toMin(a.time_start) - toMin(b.time_start)
+    })
+  }
+
   function applySnapshot(snapshot) {
     session.value = snapshot.session
-    blocks.value = snapshot.blocks || []
+    blocks.value = sortBlocksByTime(snapshot.blocks)
     completedBlockIds.value = snapshot.completed_block_ids || []
     isPaused.value = false
     if (snapshot.child) child.value = snapshot.child