feat: Implement SSH Agent Connector and gRPC server

- Added `AgentConnectorTrait` and `AgentConnector` for managing agent connections.
- Introduced `SshAgentConnector` to handle SSH-related functionalities and start a gRPC server.
- Created database entities for `agents`, `certificates`, `organizations`, `public_key_revocations`, `setup_tokens`, `upstreams`, `users`, `virtual_hosts`, and `workspaces` using SeaORM.
- Developed `CertificateService` for managing certificate generation and retrieval.
- Implemented the main server logic to initialize the database connection and start the agent server.
- Configured development settings in `development.toml` for server and database connections.

apps/nxmesh-master/src/cli/gen_certs.rs

@@ -0,0 +1,31 @@
+use std::sync::Arc;
+
+use tracing::{error, info};
+
+use crate::{config::settings::Settings, db, service};
+
+pub async fn gen_certs(
+    settings: &Settings,
+    output: String,
+) -> Result<(), Box<dyn std::error::Error>> {
+    info!("Generating CA certificate to output directory: {}", output);
+    use service::certificate::CertificateService;
+    let cert_service = service::certificate::CertificateServiceImpl::new(
+        #[expect(clippy::expect_used)]
+        db::establish_connection(&settings.database.url)
+            .await
+            .expect("Failed to connect to database"),
+        output.to_string(),
+        Arc::new(settings.clone()),
+    );
+    cert_service
+        .generate_ca_cert()
+        .await
+        .map_err(|e| {
+            error!("Failed to generate CA certificate: {}", e);
+            std::process::exit(1);
+        })
+        .unwrap();
+    info!("Successfully generated CA certificate at: {}", output);
+    Ok(())
+}