eso: Phase 2 — migrate all 104 ExternalSecrets + 2 ClusterSecretStores to v1

The API rewrite half of the ESO 0.12->2.6 migration (last k8s-1.35 compat-gate
blocker). Done on chart 0.16.2, which serves BOTH external-secrets.io/v1beta1
and v1, so this is the safe window — MUST land before 0.17 removes v1beta1
(there is no conversion webhook). Pure apiVersion bump, schema is byte-identical:
106 occurrences (104 ExternalSecrets + 2 ClusterSecretStores vault-kv/vault-database)
across 73 .tf files, v1beta1 -> v1, no other field changes.

Validated live first on tandoor (single, non-coupled, synced ES): the
kubernetes_manifest apiVersion bump forces a REPLACE; the target Secret is
cascade-GC'd for ONE ~0.3s poll then ESO recreates it (identical value re-synced
from Vault, new UID) and the ES returns SecretSynced=True on v1. Running pods
keep their mounted copy through the sub-second blip. All 110 target Secrets were
snapshotted to /tmp first as a backstop.

CI applies the changed stacks serially (staged rollout); watching aggregate ES
sync back to 108 synced (2 pre-existing dead: instagram-poster, payslip-ingest).
Next: Phase 3 climb 0.16.2 -> 2.6.0.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

stacks/speedtest/main.tf

@@ -21,7 +21,7 @@ resource "kubernetes_namespace" "speedtest" {
 
 resource "kubernetes_manifest" "external_secret" {
   manifest = {
-    apiVersion = "external-secrets.io/v1beta1"
+    apiVersion = "external-secrets.io/v1"
     kind       = "ExternalSecret"
     metadata = {
       name      = "speedtest-secrets"