enhance logging for Postgres controllers

[mploski]

Description

Cleanup of our logs according to PostgreSQL Controllers Logging Strategy doc

Key Changes

• Logging strategy: established and documented 6 rules covering logger enrichment, error ownership, loop helper patterns, log levels, message format conventions, and error string format — with a quick reference cheat sheet (docs/postgresql-logging-strategy.md)
• PostgresCluster and PostgresDatabase controllers: applied all 6 rules across pkg/postgresql/cluster/core/cluster.go and pkg/postgresql/database/core/database.go — fixed double-logging violations, redundant KV pairs, inconsistent message tenses, wrong error string forms, and inline logger calls
• API validation: added +kubebuilder:validation:Pattern to DatabaseDefinition.Name (lowercase identifier, max 30 chars), clusterRef immutability, and clusterRef.name non-empty CEL validation to postgresdatabase_types.go

Testing and Verification

Created Postgres Class, Postgres Cluster and Postgres Database
reconciler.txt

Related Issues

Jira tickets, GitHub issues, Support tickets...

PR Checklist

• Code changes adhere to the project's coding standards.
• Relevant unit and integration tests are included.
• Documentation has been updated accordingly.
• All tests pass locally.
• The PR description follows the project's guidelines.

[github-actions]

CLA Assistant Lite bot:
Thank you for your submission, we really appreciate it. Like many open-source projects, we ask that you sign our Contribution License Agreement before we can accept your contribution. You can sign the CLA by just posting a Pull Request Comment with the exact sentence copied from below.

---

I have read the CLA Document and I hereby sign the CLA

---

2 out of 4 committers have signed the CLA.
✅ @minjieqiu
✅ @DmytroPI-dev
❌ @mploski
❌ @limak9182
_{You can retrigger this bot by commenting recheck in this Pull Request}

[M4KIF]

lgtm