feat(upgrade): add self-update command from Gitea Release

- Add secrets upgrade command: --check to verify, default to download and replace binary
- No database or master key required
- Support tar.gz and zip artifacts from Gitea Release

Made-with: Cursor

src/commands/config.rs

@@ -9,6 +9,7 @@ pub async fn run(action: crate::ConfigAction) -> Result<()> {
                 .await
                 .map_err(|e| anyhow::anyhow!("Database connection failed: {}", e))?;
             drop(pool);
+            println!("Database connection successful.");
 
             let cfg = Config {
                 database_url: Some(url.clone()),