Add time-based screen scheduling (e.g. Journey every morning 6-8)

New "Time-based schedule" section on the Rotation settings page: up to
4 rules, each a screen + a daily HH:MM-HH:MM window (crossing midnight
is fine, e.g. 22:00-02:00). While a rule's window is active, that
screen overrides rotation and any manual pin -- without touching
either's underlying state, so things go back to exactly how they were
once the window ends. Navidrome-playing still wins on top of a
schedule rule, same as it already does over everything else.

config.py: new schedules list (get_schedules/set_schedules), each rule
just {screen_id, start, end} -- being in the list *is* being enabled,
no separate flag (a settings row is "disabled" by leaving its screen
dropdown on "-- none --").

scheduler.py: _time_in_window() handles same-day and midnight-wrapping
windows, treats a zero-width window as never-matching (more likely a
blank settings row than an intentional all-day rule).
_active_scheduled_screen() slots into _select_screen() between
Navidrome-priority and the pin/rotation fallback.

Verified: unit tests for _time_in_window's edge cases (wraparound,
zero-width, malformed input) and the priority override, plus an
end-to-end run against the real app -- pinned a screen, added a rule
active right now, confirmed the status page switched to the scheduled
screen within one tick.

web/templates/base.html

@@ -99,7 +99,7 @@
     label { display: block; font-weight: 600; margin-bottom: 0.35rem; font-size: 0.85rem; }
     .hint { font-size: 0.78rem; color: var(--text-muted); margin: 0.35rem 0 0; }
 
-    input[type=text], input[type=password], input[type=number], select, input[type=file] {
+    input[type=text], input[type=password], input[type=number], input[type=time], select, input[type=file] {
       width: 100%;
       padding: 0.6rem 0.7rem;
       font-size: 0.95rem;

web/templates/settings_rotation.html

@@ -35,6 +35,40 @@
     </div>
   </div>
 
+  <div class="card">
+    <div class="section-label">Time-based schedule</div>
+    <p class="hint" style="margin: -0.25rem 0 1rem;">
+      Show a specific screen automatically during a daily time window --
+      handy for e.g. checking bus departures every morning. Takes priority
+      over rotation and any manual pin while active (Navidrome priority
+      above still wins over this if enabled), and reverts back on its own
+      once the window ends. A window can cross midnight (e.g. 22:00-02:00).
+      Leave a row's screen on "-- none --" to disable it.
+    </p>
+    {% for i in range(1, max_schedule_rules + 1) %}
+    {% set rule = schedules[i - 1] if i - 1 < schedules|length else None %}
+    <div class="field" style="display: flex; gap: 0.6rem; align-items: flex-end; flex-wrap: wrap;">
+      <div style="flex: 1; min-width: 160px;">
+        <label for="schedule_screen_{{ i }}">Screen</label>
+        <select id="schedule_screen_{{ i }}" name="schedule_screen_{{ i }}">
+          <option value="">-- none --</option>
+          {% for screen_id, screen in screens.items() | sort(attribute="1.display_name") %}
+          <option value="{{ screen_id }}" {{ "selected" if rule and rule.screen_id == screen_id }}>{{ screen.display_name }}</option>
+          {% endfor %}
+        </select>
+      </div>
+      <div>
+        <label for="schedule_start_{{ i }}">From</label>
+        <input type="time" id="schedule_start_{{ i }}" name="schedule_start_{{ i }}" value="{{ rule.start if rule else '' }}">
+      </div>
+      <div>
+        <label for="schedule_end_{{ i }}">To</label>
+        <input type="time" id="schedule_end_{{ i }}" name="schedule_end_{{ i }}" value="{{ rule.end if rule else '' }}">
+      </div>
+    </div>
+    {% endfor %}
+  </div>
+
   <button type="submit">Save</button>
 </form>
 {% endblock %}