fix: qualify created_at with table alias in getGrowthTrends join query

The monthly_stats CTE joined vcons, dialog, and attachments — all three
have a created_at column. The unqualified DATE_TRUNC('month', created_at)
caused 42702: column reference "created_at" is ambiguous. Fixed to v.created_at.

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

Author: howethomas

src/db/database-analytics.ts

@@ -419,8 +419,8 @@ export class SupabaseDatabaseAnalytics implements IDatabaseAnalytics {
   private async getGrowthTrends(monthsBack: number) {
     const query = `
       WITH monthly_stats AS (
-        SELECT 
-          DATE_TRUNC('month', created_at) as month,
+        SELECT
+          DATE_TRUNC('month', v.created_at) as month,
           COUNT(*) as vcon_count,
           COUNT(DISTINCT v.id) as unique_vcons,
           SUM(COALESCE(d.size_bytes, 0)) as dialog_size,
@@ -431,7 +431,7 @@ export class SupabaseDatabaseAnalytics implements IDatabaseAnalytics {
         LEFT JOIN dialog d ON d.vcon_id = v.id
         LEFT JOIN attachments a ON a.vcon_id = v.id
         WHERE v.created_at >= NOW() - INTERVAL '${monthsBack} months'
-        GROUP BY DATE_TRUNC('month', created_at)
+        GROUP BY DATE_TRUNC('month', v.created_at)
         ORDER BY month
       )
       SELECT