Fix VARCHAR vs TIME type mismatch in med_logs queries (#15)

The medication_schedules.adjusted_time column is a TIME type, but
med_logs.scheduled_time is VARCHAR. When adjusted_time values were
passed into queries against med_logs, PostgreSQL rejected the
comparison. Add _normalize_time() to convert datetime.time objects
to "HH:MM" strings at the entry points of should_send_nag,
record_nag_sent, and mark_med_taken.

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

core/adaptive_meds.py

@@ -16,6 +16,15 @@ import core.postgres as postgres
 from core.tz import user_now, user_today_for
 
 
+def _normalize_time(val):
+    """Convert datetime.time objects to 'HH:MM' strings for use in VARCHAR queries."""
+    if isinstance(val, time):
+        return val.strftime("%H:%M")
+    if val is not None:
+        return str(val)[:5]
+    return val
+
+
 def get_adaptive_settings(user_uuid: str) -> Optional[Dict]:
     """Get user's adaptive medication settings."""
     rows = postgres.select("adaptive_med_settings", {"user_uuid": user_uuid})
@@ -226,7 +235,7 @@ def calculate_adjusted_times(
 
 
 def should_send_nag(
-    user_uuid: str, med_id: str, scheduled_time: str, current_time: datetime
+    user_uuid: str, med_id: str, scheduled_time, current_time: datetime
 ) -> Tuple[bool, str]:
     """
     Determine if we should send a nag notification.
@@ -234,6 +243,8 @@ def should_send_nag(
     Returns:
         (should_nag: bool, reason: str)
     """
+    scheduled_time = _normalize_time(scheduled_time)
+
     settings = get_adaptive_settings(user_uuid)
     if not settings:
         return False, "No settings"
@@ -301,8 +312,9 @@ def should_send_nag(
     return True, "Time to nag"
 
 
-def record_nag_sent(user_uuid: str, med_id: str, scheduled_time: str):
+def record_nag_sent(user_uuid: str, med_id: str, scheduled_time):
     """Record that a nag was sent."""
+    scheduled_time = _normalize_time(scheduled_time)
     today = user_today_for(user_uuid)
 
     query = {"user_uuid": user_uuid, "medication_id": med_id, "adjustment_date": today}
@@ -353,8 +365,9 @@ def create_daily_schedule(user_uuid: str, med_id: str, base_times: List[str]):
         postgres.insert("medication_schedules", data)
 
 
-def mark_med_taken(user_uuid: str, med_id: str, scheduled_time: str):
+def mark_med_taken(user_uuid: str, med_id: str, scheduled_time):
     """Mark a medication as taken."""
+    scheduled_time = _normalize_time(scheduled_time)
     today = user_today_for(user_uuid)
 
     postgres.update(