Fix two Helm chart bugs found running against a real kind cluster

templates/enterprise-auth.yaml never set POSTGRES_ADDR/DATABASE/
USERNAME/PASSWORD at all -- enterprise-auth silently fell back to its
localhost:5432 default and could never actually reach Postgres,
crash-looping forever. Fixed to match api.yaml's existing pattern
(Service DNS name + Secret-sourced password), plus a wait-for-postgres
initContainer for the same startup-ordering reason api.yaml has one.

templates/clickhouse.yaml was missing CLICKHOUSE_DEFAULT_ACCESS_MANAGEMENT
-- same real bug docker-compose.yml had, now fixed there too: the
official image's default user lacks CREATE USER privilege without it,
so tenantprovision's -provision-tenant could never actually provision a
tenant through this chart.

Neither of these had ever been caught before because this chart had
never been installed against a real cluster -- both surfaced and were
fixed running the full "Trying the two-tenant example" walkthrough
against a real kind cluster, ending with both tenants reaching
status.phase: Active and real generated ClickHouse credentials in their
Secrets, closing /docs/phase-4-runbook.md's last remaining gap.

deploy/helm/sentry/templates/clickhouse.yaml

@@ -29,6 +29,16 @@ spec:
                 secretKeyRef:
                   name: {{ .Release.Name }}-clickhouse
                   key: password
+            # Same reasoning as docker-compose.yml's identical setting --
+            # enterprise/internal/tenantprovision needs CREATE USER/GRANT
+            # on this admin connection, which the official image's
+            # default user doesn't have without this. Confirmed the hard
+            # way: -provision-tenant failed with "Not enough
+            # privileges... grant CREATE USER ON *.*" against a real kind
+            # cluster before this was added -- this chart had never
+            # actually been exercised against a live cluster before that.
+            - name: CLICKHOUSE_DEFAULT_ACCESS_MANAGEMENT
+              value: "1"
           ports:
             - name: http
               containerPort: 8123