feat(blog): add managed PostgreSQL with synchronous replication post (#497)

## Summary

Adds a how-to blog post covering deployment of managed PostgreSQL on
Cozystack.

## What

- New page bundle at
`content/en/blog/2026-04-17-managed-postgresql-synchronous-replication/`
- Walkthrough of deploying Postgres via the Dashboard Marketplace and
via kubectl/HelmRelease
- Covers replicas (2 async, 3 with quorum-based synchronous
replication), `resourcesPreset`, storage sizing, connection credentials
retrieval, and S3-compatible backups
- Three screenshots (Marketplace, deployment form, Ready state) embedded
via `{{< figure >}}` shortcode with a fixed 720px width so they do not
stretch across the full content column

## Why

Give operators a concise, self-contained entry point for standing up
production-grade PostgreSQL with automatic failover on Cozystack,
without wading through the full managed apps reference docs. Complements
the existing PostgreSQL reference under
`/docs/v1/applications/postgres/`.

## Preview

Netlify deploy preview will render the post under
`/blog/2026/04/managed-postgresql-synchronous-replication-without-the-ops-headache/`.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Documentation**
* Added a new blog post covering managed PostgreSQL deployment with
optional synchronous replication, featuring step-by-step Dashboard
instructions, GitOps-based kubectl deployment workflows, configurable
replica counts and resource settings, and S3-compatible backup
configuration.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: tym83

content/en/blog/2026-04-17-managed-postgresql-synchronous-replication/001_marketplace.png

@@ -0,0 +1,106 @@
+---
+title: "Managed PostgreSQL with Synchronous Replication — Without the Ops Headache"
+slug: managed-postgresql-synchronous-replication-without-the-ops-headache
+date: 2026-04-17
+author: "Timur Tukaev"
+description: "Deploy production-grade PostgreSQL with automatic failover and optional synchronous replication on your own hardware in two minutes using Cozystack."
+---
+
+Setting up PostgreSQL with synchronous replication the hard way means Patroni configs, etcd clusters, pgBouncer, monitoring exporters, backup scripts, failover testing — easily a week of work before you even store a single row. And then you still need to maintain it. AWS RDS solves this but locks you into a cloud bill that grows faster than your data.
+
+What if you could get managed PostgreSQL on your own hardware in two minutes?
+
+## The solution: Cozystack Managed PostgreSQL
+
+Cozystack uses the [CloudNativePG](https://cloudnative-pg.io/) operator under the hood — one of the most mature Kubernetes-native Postgres operators available. You get automatic failover, streaming replication, and optional quorum-based synchronous replication, all managed by the platform.
+
+## Via Dashboard (the quick way)
+
+1. Open the Cozystack dashboard at `https://dashboard.<your-domain>`.
+2. Navigate to the **Marketplace** and find **Postgres**.
+
+{{< figure src="001_marketplace.png" alt="Cozystack dashboard Marketplace with the Postgres application" width="720" >}}
+
+3. Click **Deploy** and fill in the form:
+   - Enter a name (e.g., `app-postgres`).
+   - Set replicas to `2` (primary + standby with async replication) or `3` (for synchronous replication with quorum).
+   - Choose your `resourcesPreset` (nano, micro, small, medium, large).
+   - Set storage size (e.g., `10Gi`).
+   - Under PostgreSQL parameters, configure `max_connections` if needed.
+
+{{< figure src="002_replicas.png" alt="Postgres deployment form with replicas and resources configured" width="720" >}}
+
+4. Click **Deploy**. Within two minutes, you have a primary + replica setup with automatic failover.
+
+{{< figure src="005_ready.png" alt="Deployed Postgres application reporting Ready state" width="720" >}}
+
+## Via kubectl (the GitOps way)
+
+```yaml
+apiVersion: helm.toolkit.fluxcd.io/v2
+kind: HelmRelease
+metadata:
+  name: postgres-myapp
+  namespace: tenant-team1
+spec:
+  chart:
+    spec:
+      chart: postgres
+      reconcileStrategy: Revision  # Reconcile on chart version change
+      sourceRef:
+        kind: HelmRepository
+        name: cozystack-apps
+        namespace: cozy-public
+      version: 0.10.0
+  interval: 0s  # Reconcile only on spec change, not periodically
+  values:
+    replicas: 3
+    size: 10Gi
+    resourcesPreset: small
+    databases:
+      production:
+        roles:
+          admin:
+            - appuser
+    users:
+      appuser:
+        password: "your-strong-password"  # or omit this line to auto-generate
+    external: false
+```
+
+```bash
+kubectl apply -f postgres.yaml
+```
+
+## Getting connection credentials
+
+```bash
+# Primary (read-write)
+kubectl get svc -n tenant-team1 | grep postgres-myapp-rw
+
+# Replica (read-only)
+kubectl get svc -n tenant-team1 | grep postgres-myapp-ro
+
+# Password
+kubectl get secret -n tenant-team1 postgres-myapp-app \
+  -o jsonpath='{.data.password}' | base64 --decode
+```
+
+These service names are resolvable from any nested Kubernetes cluster in the same tenant — no external DNS or VPN needed.
+
+## Backups
+
+Enable S3-compatible backup storage by setting `backup.enabled: true` in the values. Recovery is a one-line config change pointing to the source cluster name and an optional RFC 3339 timestamp.
+
+## Learn more
+
+- [Managed PostgreSQL documentation](https://cozystack.io/docs/v1/applications/postgres/)
+- [Deploy Applications guide](https://cozystack.io/docs/v1/getting-started/deploy-app/)
+- [CloudNativePG operator](https://cloudnative-pg.io/docs/)
+
+## Join the community
+
+- [GitHub](https://github.com/cozystack/cozystack)
+- Telegram [group](https://t.me/cozystack)
+- Slack [group](https://kubernetes.slack.com/archives/C06L3CPRVN1) (get invite at [https://slack.kubernetes.io](https://slack.kubernetes.io))
+- [Community Meeting Calendar](https://calendar.google.com/calendar?cid=ZTQzZDIxZTVjOWI0NWE5NWYyOGM1ZDY0OWMyY2IxZTFmNDMzZTJlNjUzYjU2ZGJiZGE3NGNhMzA2ZjBkMGY2OEBncm91cC5jYWxlbmRhci5nb29nbGUuY29t)