feat(dimentorin): mentor stats endpoint public - total sessions, unique mentees, avg rating

- GET /mentors/{id}/stats (public, no auth)
- resolve mentor profile id -> user id in get_mentor_sessions (FK uses app_users.id)

imphnen-dimentorin/src/sessions/infrastructure/http/handlers/mod.rs

@@ -5,5 +5,5 @@ pub use mutation_handlers::{
 	post_book_session, post_submit_feedback, put_update_session_status,
 };
 pub use query_handlers::{
-	get_mentor_availability, get_mentor_sessions, get_my_sessions,
+	get_mentor_availability, get_mentor_sessions, get_mentor_stats, get_my_sessions,
 };

imphnen-dimentorin/src/sessions/infrastructure/http/handlers/query_handlers.rs

@@ -1,4 +1,4 @@
-use super::super::dto::{MentorAvailabilityDto, SessionListResponseDto};
+use super::super::dto::{MentorAvailabilityDto, MentorStatsDto, SessionListResponseDto};
 use crate::sessions::domain::SessionService;
 use axum::{
 	extract::{Extension, Path, Query},
@@ -68,6 +68,25 @@ pub async fn get_mentor_availability(
 	Ok(ApiSuccess(resp))
 }
 
+#[utoipa::path(
+    get,
+    path = "/v1/dimentorin/mentors/{id}/stats",
+    tag = "sessions",
+    params(
+        ("id" = String, Path, description = "Mentor id"),
+    ),
+    responses(
+        (status = 200, description = "Mentor stats retrieved successfully", body = MentorStatsDto),
+    )
+)]
+pub async fn get_mentor_stats(
+	Extension(service): Extension<Arc<dyn SessionService>>,
+	Path(mentor_id): Path<String>,
+) -> Result<impl IntoResponse, AppError> {
+	let resp = MentorStatsDto::from(service.get_mentor_stats(mentor_id).await?);
+	Ok(ApiSuccess(resp))
+}
+
 #[utoipa::path(
     get,
     path = "/v1/dimentorin/sessions/me",