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>

backend/app/schemas/schedule.py

@@ -27,6 +27,8 @@ class ScheduleTemplateCreate(BaseModel):
     name: str
     child_id: int | None = None
     is_default: bool = False
+    day_start_time: time | None = None
+    day_end_time: time | None = None
     blocks: list[ScheduleBlockCreate] = []
 
 
@@ -34,6 +36,8 @@ class ScheduleTemplateUpdate(BaseModel):
     name: str | None = None
     child_id: int | None = None
     is_default: bool | None = None
+    day_start_time: time | None = None
+    day_end_time: time | None = None
 
 
 class ScheduleTemplateOut(BaseModel):
@@ -41,6 +45,8 @@ class ScheduleTemplateOut(BaseModel):
     name: str
     child_id: int | None
     is_default: bool
+    day_start_time: time | None
+    day_end_time: time | None
     blocks: list[ScheduleBlockOut] = []
 
     model_config = {"from_attributes": True}