feat: historial de cambios (usuario, fecha, detalle)

Tabla change_history, pantalla en Agencia OS y registro automático
al guardar o enriquecer Zona de marca.

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

src/app/api/change-history/route.ts

@@ -0,0 +1,80 @@
+/**
+ * GET /api/change-history — listado del historial de cambios.
+ * Query: tenant_id?, entity_type?, limit?, offset?
+ */
+import { NextRequest, NextResponse } from 'next/server';
+import { createClient } from '@/lib/supabase/server';
+import { homeTenantId, isAgencyRole, userRole } from '@/lib/agency';
+import { listChangeHistory } from '@/lib/change-history';
+import { resolveActiveTenant } from '@/lib/tenant-context';
+
+export const dynamic = 'force-dynamic';
+
+export async function GET(req: NextRequest) {
+  const supabase = await createClient();
+  const {
+    data: { user },
+  } = await supabase.auth.getUser();
+  if (!user) {
+    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 });
+  }
+
+  const role = userRole(user);
+  const isAgency = isAgencyRole(role);
+  const sp = req.nextUrl.searchParams;
+  const limit = Number(sp.get('limit') || 50);
+  const offset = Number(sp.get('offset') || 0);
+  const entityType = sp.get('entity_type') || sp.get('entityType') || null;
+
+  let tenantId =
+    sp.get('tenant_id') || sp.get('tenantId') || null;
+
+  if (!isAgency) {
+    // Cliente: solo su tenant
+    const own = homeTenantId(user);
+    const ctx = await resolveActiveTenant(user);
+    tenantId = own || ctx.tenantId || null;
+    if (!tenantId) {
+      return NextResponse.json({ error: 'Sin tenant' }, { status: 400 });
+    }
+  } else if (!tenantId) {
+    // Agencia sin filtro: usa contexto activo si hay cliente seleccionado
+    const ctx = await resolveActiveTenant(user);
+    if (ctx.tenantId && !ctx.portfolioWide) {
+      tenantId = ctx.tenantId;
+    }
+    // Si portfolio wide, tenantId queda null → historial global
+  }
+
+  const { rows, error } = await listChangeHistory({
+    tenantId,
+    entityType,
+    limit,
+    offset,
+  });
+
+  if (error) {
+    const missing =
+      /relation .*change_history.* does not exist|Could not find the table/i.test(
+        error
+      );
+    return NextResponse.json(
+      {
+        ok: false,
+        error: missing
+          ? 'Falta crear la tabla change_history (sql/change_history.sql).'
+          : error,
+        rows: [],
+        needsMigration: missing,
+      },
+      { status: missing ? 503 : 500 }
+    );
+  }
+
+  return NextResponse.json({
+    ok: true,
+    rows,
+    tenant_id: tenantId,
+    portfolio_wide: isAgency && !tenantId,
+  });
+}