Add docker build, rewrite Actions for Gitea, and add healthcheck endpoint.

src/routes/health.rs

@@ -0,0 +1,8 @@
+use axum::response::{IntoResponse, Json};
+use serde_json::json;
+
+/// GET /health
+/// Returns a simple health-check response for liveness probes.
+pub async fn health() -> impl IntoResponse {
+    Json(json!({"status": "ok"}))
+}