chore: bump tower + tower-ui to 0.66.20

- Wizard: default Odoo to latest matrix entry; PG snaps to recommended
  on every Odoo change (was sticky-compatible, leaving PG 16 when
  switching to Odoo 19 even though 17 is recommended)
- export.go: pgClientImageFor(shape.PostgresVersion) — pg_dump tracks
  source instances actual PG version (17/18/whatever ships next)

values.yaml

@@ -9,7 +9,7 @@ backend:
     # so every cluster that runs Tower needs the same imagePullSecret
     # provisioned out-of-band (until cluster-platform-v3 owns it).
     repository: registry.odoosky.cloud/odoosky/docker-mirror/tower
-    tag: "0.66.19"
+    tag: "0.66.20"
     pullPolicy: IfNotPresent
   imagePullSecrets:
     - name: docker-mirror-pull
@@ -29,7 +29,7 @@ frontend:
   enabled: true
   image:
     repository: registry.odoosky.cloud/odoosky/docker-mirror/tower-ui
-    tag: "0.66.18"
+    tag: "0.66.20"
     pullPolicy: IfNotPresent
   imagePullSecrets:
     - name: docker-mirror-pull