Fix month-change MetricasDiarias overwrite bug, add per-date Ads metrics helpers

On month change, run.py redirected the write to the previous month's
GACampaignMes record but built the JSON from the new month's near-empty
record, overwriting the previous month's full daily history with just
the redirected day. Now it merges with the previous month's real
MetricasDiarias (via get_metricas_diarias_prev_month) before writing.

Also add get_metrics_for_date() and get_daily_metrics_for_month() to
GoogleAdsClient for reconstructing historical daily cost/conversions,
needed by the backfill scripts.

google_ads_client.py

@@ -100,6 +100,70 @@ class GoogleAdsClient:
             print(f"  ❌ Error obteniendo métricas de hoy: {e}")
         return result
 
+    def get_metrics_for_date(self, date_str: str) -> dict:
+        """
+        Devuelve métricas de una fecha concreta ('YYYY-MM-DD') para TODAS las
+        campañas en una sola query. Retorna dict {campaign_id: {conversions, cost}}.
+        """
+        ga_service = self.client.get_service("GoogleAdsService")
+        query = f"""
+            SELECT
+                campaign.id,
+                metrics.conversions,
+                metrics.cost_micros
+            FROM campaign
+            WHERE campaign.status != 'REMOVED'
+              AND segments.date = '{date_str}'
+        """
+        result = {}
+        try:
+            response = ga_service.search(customer_id=self.customer_id, query=query)
+            for row in response:
+                cid = str(row.campaign.id)
+                result[cid] = {
+                    "conversions": row.metrics.conversions,
+                    "cost": row.metrics.cost_micros / 1_000_000,
+                }
+        except GoogleAdsException as e:
+            print(f"  ❌ Error obteniendo métricas del {date_str}: {e}")
+        return result
+
+    def get_daily_metrics_for_month(self, year: int, month: int) -> dict:
+        """
+        Devuelve coste y conversiones diarias de todas las campañas para un mes
+        completo. Retorna dict {date_str ('YYYY-MM-DD'): {campaign_id: {cost, conversions}}}.
+        """
+        start = f"{year}-{month:02d}-01"
+        if month == 12:
+            end = f"{year + 1}-01-01"
+        else:
+            end = f"{year}-{month + 1:02d}-01"
+        ga_service = self.client.get_service("GoogleAdsService")
+        query = f"""
+            SELECT
+                campaign.id,
+                segments.date,
+                metrics.conversions,
+                metrics.cost_micros
+            FROM campaign
+            WHERE campaign.status != 'REMOVED'
+              AND segments.date >= '{start}'
+              AND segments.date < '{end}'
+        """
+        result: dict = {}
+        try:
+            response = ga_service.search(customer_id=self.customer_id, query=query)
+            for row in response:
+                date_str = row.segments.date
+                cid = str(row.campaign.id)
+                result.setdefault(date_str, {})[cid] = {
+                    "conversions": row.metrics.conversions,
+                    "cost": row.metrics.cost_micros / 1_000_000,
+                }
+        except GoogleAdsException as e:
+            print(f"  ❌ Error obteniendo métricas diarias del mes: {e}")
+        return result
+
     def get_daily_conversions_for_month(self, year: int, month: int) -> dict:
         """
         Devuelve conversiones diarias de todas las campañas para un mes completo.

run.py

@@ -398,8 +398,13 @@ def run():
     if metricas_updates:
         print(f"→ Actualizando MetricasDiarias ({len(metricas_updates)} registros)...")
         if cambio_mes:
-            # Ayer pertenece al mes anterior: redirigir escritura al GACampaignMes correcto
+            # Ayer pertenece al mes anterior: redirigir escritura al GACampaignMes correcto.
+            # El "campaign" en memoria es el del mes nuevo (recién creado, MetricasDiarias
+            # casi vacío) — hay que hacer merge con el MetricasDiarias REAL del mes anterior
+            # antes de escribir, o se pierde el resto de días ya acumulados (bug que borró
+            # el histórico de junio salvo el día 30 al hacer un overwrite directo).
             prev_map = at.get_gcm_id_map_for_month(ayer.month, ayer.year)
+            prev_metricas = at.get_metricas_diarias_prev_month()
             redirected = []
             omitidos = []
             for u in metricas_updates:
@@ -409,7 +414,14 @@ def run():
                     None,
                 )
                 if gid and gid in prev_map:
+                    try:
+                        existing_md = json.loads(prev_metricas.get(gid, {}).get("metricas") or "{}")
+                    except (json.JSONDecodeError, TypeError):
+                        existing_md = {}
+                    nuevo_dia_md = json.loads(u["metricas_json"])
+                    existing_md.update(nuevo_dia_md)
                     u["airtable_id"] = prev_map[gid]
+                    u["metricas_json"] = json.dumps(existing_md, ensure_ascii=False)
                     redirected.append(u)
                 else:
                     omitidos.append(gid)