feat: columna ad_daily.link_clicks (Meta clics enlace reales)

Persistimos link_clicks en warehouse (con backfill desde __lc), sync escribe la columna y creatividades la leen sin romper si falta.

Co-authored-by: Cursor <cursoragent@cursor.com>

sql/ad_daily_link_clicks.sql

@@ -1,3 +1,18 @@
 -- Meta: clics en el enlace (Ads Manager) aparte de clicks = clics todos.
 ALTER TABLE public.ad_daily
   ADD COLUMN IF NOT EXISTS link_clicks numeric(14, 6) NOT NULL DEFAULT 0;
+
+-- Backfill from legacy Meta marker stored in ad_name (`__lc:N`).
+UPDATE public.ad_daily
+SET link_clicks = (regexp_match(ad_name, '^__lc:([0-9.]+)$'))[1]::numeric
+WHERE platform = 'meta'
+  AND ad_name ~ '^__lc:'
+  AND (link_clicks IS NULL OR link_clicks = 0);
+
+-- Google: link clicks ≈ all clicks at campaign level.
+UPDATE public.ad_daily
+SET link_clicks = clicks
+WHERE platform = 'google'
+  AND (link_clicks IS NULL OR link_clicks = 0)
+  AND clicks IS NOT NULL
+  AND clicks > 0;