refactor: extract dereference/validate pipeline from reconcile (#889)

* refactor(controller): introduce dereference module (unused)

* refactor(controller): introduce validate module (unused)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* refactor(controller): run dereference and validate first in reconcile

* refactor(controller): drop unused namespace and restore test

Remove the unused `namespace` field from `ValidatedInputs` and its
corresponding `MissingTrinoNamespace` error variant, along with the
`let _ = &validated.namespace` workaround in `reconcile_trino`.
Expose `validated_product_config` as `pub(super)` so `test_env_overrides`
can call it directly instead of inlining the 30-line equivalent.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix: regenerate crate hashes

* fix: remove obsolete error

* fix: run pre-commit

* fix: consolidate validate_cluster name

* fix: remove strum derives

* Revert "fix: consolidate validate_cluster name"

This reverts commit 55cf40f.

* fix: rename resolved_product_image -> image

* fix: reorder validate paramters

* docs: adapted changelog

* feat: add test snapshot to smoke

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: maltesander

CHANGELOG.md

@@ -19,6 +19,7 @@ All notable changes to this project will be documented in this file.
   but ignored ([#878]).
 - Document Helm deployed RBAC permissions and remove unnecessary permissions ([#869]).
 - Bump `stackable-operator` to 0.111.0 and `kube` to 3.1.0 ([#878], [#884]).
+- Internal operator refactoring: introduce dereference() and validate() steps in the reconciler ([#889]).
 
 ### Fixed
 
@@ -34,6 +35,7 @@ All notable changes to this project will be documented in this file.
 [#878]: https://github.com/stackabletech/trino-operator/pull/878
 [#883]: https://github.com/stackabletech/trino-operator/pull/883
 [#884]: https://github.com/stackabletech/trino-operator/pull/884
+[#889]: https://github.com/stackabletech/trino-operator/pull/889
 
 ## [26.3.0] - 2026-03-16