Grafana fails to become healthy

I have enabled Grafana service as shown [in the docs](https://community.flake.parts/services-flake/grafana), and it runs but fails imidiately because of the read-only file system in nix store (obviously on nix).

## Here is my code:
```nix
{ config, lib, pkgs, ... }:
{
options = {
services.monitoring = {
enable = lib.mkEnableOption "Enable grafana stack";
package = lib.mkPackageOption pkgs "monitoring" { };
};
};
config =
let
cfg = config.services.monitoring;
in
lib.mkIf cfg.enable {
services.grafana.gf1 = {
enable = true;
};
};
}
```

I get this error:
```
Error: x failed to connect to database: failed to create SQLite database file "/nix/store/1km88kkjcrdn3vybwvx74pvfaxrhc44f-grafana-12.0.0+security-01/share/
grafana/grafana.db": open /nix/store/1km88kkjcrdn3vybwvx74pvfaxrhc44f-grafana-12.0.0+security-01/share/grafana/grafana.db: read-only file system
```

It can't create database, because nix doesn't allow it. As a workaround I did the setup for DB myself, but grafana still tries to write something to the readonly filesystem.

## New code with DB setup
```nix
{ config, lib, pkgs, ... }:
{
options = {
services.monitoring = {
enable = lib.mkEnableOption "Enable grafana stack";
package = lib.mkPackageOption pkgs "monitoring" { };
};
};
config =
let
cfg = config.services.monitoring;
in
lib.mkIf cfg.enable {

services.postgres.pg-grafana = {
enable = true;
listen_addresses = "127.0.0.127";
initialScript.after = "CREATE USER root SUPERUSER;";
};

services.grafana.gf1 = {
enable = true;
extraConf.database = with config.services.postgres.pg-grafana; {
type = "postgres";
host = "${listen_addresses}:${builtins.toString port}";
name = "postgres"; # database name
};
};

settings.processes."gf1".depends_on."pg-grafana".condition = "process_healthy";
};
}

```

And it fails with this error:
```
logger=secrets t=2025-09-05T10:35:29.559024542+09:00 level=info msg="Envelope encryption state" enabled=true currentprovider=secretKey.vl

Error: x failed to create directory "/nix/store/1km88kkjcrdn3vybwvx74pvfaxrhc44f-grafana-12.0.0+security-01/share/grafana/png": mkdir /nix/store/
1km88kkjcrdn3vybwvx74pvfaxrhc44f-grafana-12.0.0+security-01/share/grafana/png: read-only file system
```

Looks like grafana package is not patched to be used within the nix ecosystem?