feat: [#246] add Grafana service configuration to UserInputs

- Add grafana field as Option<GrafanaConfig> to UserInputs struct
- Enable Grafana by default (opt-out, matching Prometheus behavior)
- Update all UserInputs initializers with grafana: Some(GrafanaConfig::default())
- Add GrafanaConfig import to testing modules (mod.rs and testing.rs)
- Replace long namespaces with short type names (TrackerConfig, PrometheusConfig)
- Update documentation to reflect Grafana-Prometheus dependency requirement

The grafana field follows the same pattern as prometheus - enabled by default
and can be disabled by setting to None. Grafana requires Prometheus to be
enabled, which will be validated at configuration time in subsequent commits.

Author: josecelano

src/domain/environment/mod.rs

@@ -896,7 +896,10 @@ impl<S> Environment<S> {
 mod tests {
     use super::*;
     use crate::adapters::ssh::SshCredentials;
+    use crate::domain::grafana::GrafanaConfig;
+    use crate::domain::prometheus::PrometheusConfig;
     use crate::domain::provider::{LxdConfig, ProviderConfig};
+    use crate::domain::tracker::TrackerConfig;
     use crate::domain::EnvironmentName;
     use std::path::Path;
     use tempfile::TempDir;
@@ -1042,8 +1045,9 @@ mod tests {
                     provider_config,
                     ssh_credentials,
                     ssh_port: 22,
-                    tracker: crate::domain::tracker::TrackerConfig::default(),
-                    prometheus: Some(crate::domain::prometheus::PrometheusConfig::default()),
+                    tracker: TrackerConfig::default(),
+                    prometheus: Some(PrometheusConfig::default()),
+                    grafana: Some(GrafanaConfig::default()),
                 },
                 internal_config: InternalConfig {
                     data_dir: data_dir.clone(),

src/domain/environment/testing.rs

@@ -5,7 +5,9 @@
 
 use super::*;
 use crate::adapters::ssh::SshCredentials;
+use crate::domain::grafana::GrafanaConfig;
 use crate::domain::provider::{LxdConfig, ProviderConfig};
+use crate::domain::tracker::TrackerConfig;
 use crate::domain::EnvironmentName;
 use crate::shared::Username;
 use std::path::{Path, PathBuf};
@@ -144,16 +146,17 @@ impl EnvironmentTestBuilder {
         let provider_config = ProviderConfig::Lxd(LxdConfig { profile_name });
 
         let context = EnvironmentContext {
-            user_inputs: crate::domain::environment::UserInputs {
+            user_inputs: UserInputs {
                 name: env_name,
                 instance_name,
                 provider_config,
                 ssh_credentials,
                 ssh_port: 22,
-                tracker: crate::domain::tracker::TrackerConfig::default(),
+                tracker: TrackerConfig::default(),
                 prometheus: self.prometheus_config,
+                grafana: Some(GrafanaConfig::default()),
             },
-            internal_config: crate::domain::environment::InternalConfig {
+            internal_config: InternalConfig {
                 data_dir: data_dir.clone(),
                 build_dir: build_dir.clone(),
             },

src/domain/environment/user_inputs.rs

@@ -20,6 +20,7 @@
 
 use crate::adapters::ssh::SshCredentials;
 use crate::domain::environment::EnvironmentName;
+use crate::domain::grafana::GrafanaConfig;
 use crate::domain::prometheus::PrometheusConfig;
 use crate::domain::provider::{Provider, ProviderConfig};
 use crate::domain::tracker::TrackerConfig;
@@ -40,6 +41,7 @@ use serde::{Deserialize, Serialize};
 /// use torrust_tracker_deployer_lib::domain::environment::user_inputs::UserInputs;
 /// use torrust_tracker_deployer_lib::domain::tracker::TrackerConfig;
 /// use torrust_tracker_deployer_lib::domain::prometheus::PrometheusConfig;
+/// use torrust_tracker_deployer_lib::domain::grafana::GrafanaConfig;
 /// use torrust_tracker_deployer_lib::shared::Username;
 /// use torrust_tracker_deployer_lib::adapters::ssh::SshCredentials;
 /// use std::path::PathBuf;
@@ -60,6 +62,7 @@ use serde::{Deserialize, Serialize};
 ///     ssh_port: 22,
 ///     tracker: TrackerConfig::default(),
 ///     prometheus: Some(PrometheusConfig::default()),
+///     grafana: Some(GrafanaConfig::default()),
 /// };
 /// # Ok::<(), Box<dyn std::error::Error>>(())
 /// ```
@@ -89,6 +92,14 @@ pub struct UserInputs {
     /// When absent (`None`), Prometheus service is disabled.
     /// Default: `Some(PrometheusConfig::default())` in generated templates.
     pub prometheus: Option<PrometheusConfig>,
+
+    /// Grafana visualization and dashboard configuration (optional)
+    ///
+    /// When present, Grafana service is enabled in the deployment.
+    /// When absent (`None`), Grafana service is disabled.
+    /// Requires Prometheus to be enabled - dependency validated at configuration time.
+    /// Default: `Some(GrafanaConfig::default())` in generated templates.
+    pub grafana: Option<GrafanaConfig>,
 }
 
 impl UserInputs {
@@ -156,6 +167,7 @@ impl UserInputs {
             ssh_port,
             tracker: TrackerConfig::default(),
             prometheus: Some(PrometheusConfig::default()),
+            grafana: Some(GrafanaConfig::default()),
         }
     }
 
@@ -181,6 +193,7 @@ impl UserInputs {
             ssh_port,
             tracker,
             prometheus: Some(PrometheusConfig::default()),
+            grafana: Some(GrafanaConfig::default()),
         }
     }