Add time-based day progress bar to dashboards

Replaces block-count progress with a wall-clock progress bar driven by
configurable day start/end hours on each schedule template.

- ScheduleTemplate: add day_start_time / day_end_time (TIME, nullable)
- Startup migration: idempotent ALTER TABLE for existing DBs
- Dashboard snapshot: includes day_start_time / day_end_time from template
- Admin → Schedules: time pickers in block editor to set day hours
- Dashboard view: time-based progress bar with start/current/end labels
- TV view: full-width day progress strip between header and main content

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

frontend/src/stores/schedule.js

@@ -10,6 +10,8 @@ export const useScheduleStore = defineStore('schedule', () => {
   const isPaused = ref(false)
   const blockStartedAt = ref(null)    // Date.now() ms when current counting period started
   const blockElapsedOffset = ref(0)   // seconds already elapsed before blockStartedAt
+  const dayStartTime = ref(null)      // "HH:MM:SS" string or null
+  const dayEndTime = ref(null)        // "HH:MM:SS" string or null
 
   const currentBlock = computed(() =>
     session.value?.current_block_id
@@ -28,6 +30,8 @@ export const useScheduleStore = defineStore('schedule', () => {
     completedBlockIds.value = snapshot.completed_block_ids || []
     isPaused.value = false
     if (snapshot.child) child.value = snapshot.child
+    dayStartTime.value = snapshot.day_start_time || null
+    dayEndTime.value = snapshot.day_end_time || null
     // Restore elapsed time from server-computed value
     const serverElapsed = snapshot.block_elapsed_seconds || 0
     if (snapshot.session?.current_block_id && serverElapsed > 0) {
@@ -111,6 +115,8 @@ export const useScheduleStore = defineStore('schedule', () => {
     isPaused,
     blockStartedAt,
     blockElapsedOffset,
+    dayStartTime,
+    dayEndTime,
     currentBlock,
     progressPercent,
     applySnapshot,