fix(infra): address PR review feedback on tf modules

Deployer role:
- Add servicediscovery actions; module always creates Cloud Map namespace
  and service so the policy must grant CreatePrivateDnsNamespace etc.
- Make Route53 + ACM permissions unconditional. The server module always
  issues an ACM cert and writes Route53 records (no CloudFront default-cert
  path exists), so gating these on route53_zone_ids was broken. Split
  Route53 into hosted-zone management (always) plus record-set mutation
  (scoped to caller-supplied zones, falls back to *).
- Remove unused cloudfront:* statement; no CloudFront resources in module.
- Replace acm:* wildcard with explicit cert-management action set.

Server module:
- qdrant_image_tag is now nullable with default null and validated against
  use_external_qdrant, so external-qdrant callers can omit it instead of
  passing a sentinel "unused" value.
- task_role_arn and efs_id outputs marked sensitive; qdrant_dns_name returns
  null when use_external_qdrant = true.
- ALB SG now has matching IPv6 egress rule (was v4-only).
- nextcloud_url validates the https:// scheme.
- random_pet.subdomain keeper includes zone_name so a zone migration that
  preserves zone_id still triggers regeneration.
- Pin required_version >= 1.9 on both modules.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

infra/terraform/README.md

@@ -228,8 +228,8 @@ module "nextcloud_mcp_server" {
   secret_arn = "arn:aws:secretsmanager:eu-west-1:123456789012:secret:nextcloud-mcp-aws-env-XXXXXX"
 
   use_external_qdrant = true
-  qdrant_image_tag    = "unused" # required input but ignored when use_external_qdrant=true
   qdrant_collection   = "nextcloud-mcp"
+  # qdrant_image_tag intentionally omitted — only required when use_external_qdrant = false.
 }
 ```