fix: use psycopg2 placeholders (%s) not PostgreSQL ($N)

Bug 1 Final Fix:
- Changed all placeholders from $1, $2, $3 to %s
- psycopg2 expects Python-style %s, converts to $N internally
- Using $N directly causes 'there is no parameter $1' error
- Removed param_idx counter (not needed with %s)

Root cause: Mixing PostgreSQL native syntax with psycopg2 driver
This is THE fix that will finally work!

backend/routers/vitals_baseline.py

@@ -109,63 +109,54 @@ def create_or_update_baseline(
     # Always include profile_id and date
     param_values.append(pid)
     param_values.append(entry.date)
-    param_idx = 3  # Next parameter starts at $3
 
     if entry.resting_hr is not None:
         insert_cols.append("resting_hr")
-        insert_placeholders.append(f"${param_idx}")
-        update_fields.append(f"resting_hr = EXCLUDED.resting_hr")
+        insert_placeholders.append("%s")
+        update_fields.append("resting_hr = EXCLUDED.resting_hr")
         param_values.append(entry.resting_hr)
-        param_idx += 1
 
     if entry.hrv is not None:
         insert_cols.append("hrv")
-        insert_placeholders.append(f"${param_idx}")
-        update_fields.append(f"hrv = EXCLUDED.hrv")
+        insert_placeholders.append("%s")
+        update_fields.append("hrv = EXCLUDED.hrv")
         param_values.append(entry.hrv)
-        param_idx += 1
 
     if entry.vo2_max is not None:
         insert_cols.append("vo2_max")
-        insert_placeholders.append(f"${param_idx}")
-        update_fields.append(f"vo2_max = EXCLUDED.vo2_max")
+        insert_placeholders.append("%s")
+        update_fields.append("vo2_max = EXCLUDED.vo2_max")
         param_values.append(entry.vo2_max)
-        param_idx += 1
 
     if entry.spo2 is not None:
         insert_cols.append("spo2")
-        insert_placeholders.append(f"${param_idx}")
-        update_fields.append(f"spo2 = EXCLUDED.spo2")
+        insert_placeholders.append("%s")
+        update_fields.append("spo2 = EXCLUDED.spo2")
         param_values.append(entry.spo2)
-        param_idx += 1
 
     if entry.respiratory_rate is not None:
         insert_cols.append("respiratory_rate")
-        insert_placeholders.append(f"${param_idx}")
-        update_fields.append(f"respiratory_rate = EXCLUDED.respiratory_rate")
+        insert_placeholders.append("%s")
+        update_fields.append("respiratory_rate = EXCLUDED.respiratory_rate")
         param_values.append(entry.respiratory_rate)
-        param_idx += 1
 
     if entry.body_temperature is not None:
         insert_cols.append("body_temperature")
-        insert_placeholders.append(f"${param_idx}")
-        update_fields.append(f"body_temperature = EXCLUDED.body_temperature")
+        insert_placeholders.append("%s")
+        update_fields.append("body_temperature = EXCLUDED.body_temperature")
         param_values.append(entry.body_temperature)
-        param_idx += 1
 
     if entry.resting_metabolic_rate is not None:
         insert_cols.append("resting_metabolic_rate")
-        insert_placeholders.append(f"${param_idx}")
-        update_fields.append(f"resting_metabolic_rate = EXCLUDED.resting_metabolic_rate")
+        insert_placeholders.append("%s")
+        update_fields.append("resting_metabolic_rate = EXCLUDED.resting_metabolic_rate")
         param_values.append(entry.resting_metabolic_rate)
-        param_idx += 1
 
     if entry.note:
         insert_cols.append("note")
-        insert_placeholders.append(f"${param_idx}")
-        update_fields.append(f"note = EXCLUDED.note")
+        insert_placeholders.append("%s")
+        update_fields.append("note = EXCLUDED.note")
         param_values.append(entry.note)
-        param_idx += 1
 
     # At least one field must be provided
     if not insert_cols:
@@ -175,8 +166,9 @@ def create_or_update_baseline(
         cur = get_cursor(conn)
 
         # Build complete column list and placeholder list
+        # IMPORTANT: psycopg2 uses %s placeholders, NOT $1/$2/$3
         all_cols = f"profile_id, date, {', '.join(insert_cols)}"
-        all_placeholders = f"$1, $2, {', '.join(insert_placeholders)}"
+        all_placeholders = f"%s, %s, {', '.join(insert_placeholders)}"
 
         query = f"""
             INSERT INTO vitals_baseline ({all_cols})