feat: PostgreSQL driver support

docs/deployment.md

@@ -8,7 +8,7 @@ RenewCMS ships as **one self-contained executable**. It serves:
 | `/healthz` | Liveness check, returns `200 ok`        |
 | `/*`       | The Vue SPA (embedded), with fallback to `index.html` for client-side routes |
 
-Runtime state includes the SQLite database (`DB_FILE`, or a MySQL/MariaDB server, see [Using MySQL or MariaDB](#using-mysql-or-mariadb)), uploads (`UPLOAD_DIR`, or an S3-compatible bucket with `STORAGE_DRIVER=s3`, see [configuration.md](configuration.md#image-storage)), and update records, staged binaries and backups beside the database. Running a release binary needs no Go, Bun or Node installation. Browser updates additionally require Linux with systemd and the helper setup below.
+Runtime state includes the SQLite database (`DB_FILE`, or a MySQL/MariaDB or PostgreSQL server, see [Using MySQL or MariaDB](#using-mysql-or-mariadb) and [Using PostgreSQL](#using-postgresql)), uploads (`UPLOAD_DIR`, or an S3-compatible bucket with `STORAGE_DRIVER=s3`, see [configuration.md](configuration.md#image-storage)), and update records, staged binaries and backups beside the database. Running a release binary needs no Go, Bun or Node installation. Browser updates additionally require Linux with systemd and the helper setup below.
 
 To run it in a container instead, see [docker.md](docker.md). The published image `git.floriansylvain.fr/fsylvain/renewcms` is upgraded with `docker compose pull && docker compose up -d`. Tags are `vX.Y.Z`, `X.Y.Z`, `X.Y` and `latest` for a stable release, and `vX.Y.Z-<pre>`, `X.Y.Z-<pre>` and the moving `<pre-name>` (`beta`, `rc`) for a pre-release, which never moves `latest`. Maintainers publish with `task docker:publish` after `docker login git.floriansylvain.fr`; there is no CI. See [Maintainer: publishing](docker.md#maintainer-publishing).
 
@@ -292,6 +292,22 @@ DATA_DIR=/var/lib/renewcms
 
 `DB_FILE` is then ignored. `DATA_DIR` is where update state, staged updates and backups live, so give it the same value as the helper's `--data-dir` (see [browser updates](#browser-updates)). Use `DB_TLS=true` (or `preferred`) whenever the server is not on the same host. Every variable is described in [configuration.md](configuration.md#database). The schema is created and migrated at startup, so the first start on an empty database needs nothing else.
 
+## Using PostgreSQL
+
+To use an existing PostgreSQL 16 or 17 server, create an empty database and a user with full rights on its `public` schema, then set in `/etc/renewcms/renewcms.env`:
+
+```sh
+DB_DRIVER=postgres
+DB_HOST=db.example.com
+DB_USER=renewcms
+DB_PASSWORD=<generated password>
+DB_NAME=renewcms
+DB_SSLMODE=require
+DATA_DIR=/var/lib/renewcms
+```
+
+`DB_FILE` is then ignored, and `DB_PORT` defaults to `5432`. `DATA_DIR` is where update state, staged updates and backups live, so give it the same value as the helper's `--data-dir`. Use `DB_SSLMODE=require` (or `verify-full`) whenever the server is not on the same host. Every variable is described in [configuration.md](configuration.md#database). The schema is created and migrated at startup. Moving an existing SQLite site is a manual procedure like the MySQL one below, and RenewCMS writes a logical `.sql` dump to `DATA_DIR/backups` before each update download.
+
 ### Moving an existing SQLite site to MySQL
 
 There is no migration tool. The manual procedure, with the site stopped:
@@ -305,7 +321,7 @@ Keep the SQLite file until you have checked the site.
 
 ## Backups
 
-With MySQL or MariaDB, back the database up with your server's own tools (for example `mysqldump --single-transaction`), plus the uploads directory. RenewCMS also writes a logical dump to `DATA_DIR/backups` before each update download. The rest of this section is about SQLite.
+With MySQL, MariaDB or PostgreSQL, back the database up with your server's own tools (for example `mysqldump --single-transaction` or `pg_dump`), plus the uploads directory. RenewCMS also writes a logical dump to `DATA_DIR/backups` before each update download. The rest of this section is about SQLite.
 
 Everything worth backing up is under the data directory. Take a consistent SQLite copy while the service is running: