cli: avoid data-dir initialization for version; create db parent dirs; redact generated passwords in CLI output

- Prevent 'nx9-wg version' from creating data directories by avoiding database initialization.
- Create parent directories when an explicit --database path is provided.
- Redact printed generated administrator passwords; announce file path or redact instead.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

crates/nx9-wg-db/src/lib.rs

@@ -0,0 +1,28 @@
+//! SQLite persistence layer for nx9-wg.
+//!
+//! Provides the authoritative desired-state storage, administrator identity,
+//! authentication state, interfaces, peers, networks, routes, firewall rules,
+//! system settings, backup metadata, and audit records.
+
+pub mod admin;
+pub mod audit;
+pub mod backups;
+pub mod client_profiles;
+pub mod error;
+pub mod firewall;
+pub mod interfaces;
+pub mod login_attempts;
+pub mod migrations;
+pub mod models;
+pub mod networks;
+pub mod peers;
+pub mod routes;
+pub mod sessions;
+pub mod settings;
+pub mod store;
+pub mod tokens;
+
+pub use audit::AuditFilter;
+pub use error::{DbError, Result};
+pub use migrations::run_migrations;
+pub use store::Store;