feat: transport protocol tracking (UDP/TCP/DoT/DoH) with dashboard visualization

Thread Transport enum through resolve pipeline, record per-query
transport in stats and query log. Dashboard gets bar chart panel
with encryption %, transport column in query log, and filter dropdown.

src/api.rs

@@ -152,6 +152,7 @@ struct QueryLogResponse {
     domain: String,
     query_type: String,
     path: String,
+    transport: String,
     rescode: String,
     latency_ms: f64,
     dnssec: String,
@@ -167,6 +168,7 @@ struct StatsResponse {
     dnssec: bool,
     srtt: bool,
     queries: QueriesStats,
+    transport: TransportStats,
     cache: CacheStats,
     overrides: OverrideStats,
     blocking: BlockingStatsResponse,
@@ -175,6 +177,14 @@ struct StatsResponse {
     memory: MemoryStats,
 }
 
+#[derive(Serialize)]
+struct TransportStats {
+    udp: u64,
+    tcp: u64,
+    dot: u64,
+    doh: u64,
+}
+
 #[derive(Serialize)]
 struct MobileStatsResponse {
     enabled: bool,
@@ -483,6 +493,7 @@ async fn query_log(
                     domain: e.domain.clone(),
                     query_type: e.query_type.as_str().to_string(),
                     path: e.path.as_str().to_string(),
+                    transport: e.transport.as_str().to_string(),
                     rescode: e.rescode.as_str().to_string(),
                     latency_ms: e.latency_us as f64 / 1000.0,
                     dnssec: e.dnssec.as_str().to_string(),
@@ -545,6 +556,12 @@ async fn stats(State(ctx): State<Arc<ServerCtx>>) -> Json<StatsResponse> {
             blocked: snap.blocked,
             errors: snap.errors,
         },
+        transport: TransportStats {
+            udp: snap.transport_udp,
+            tcp: snap.transport_tcp,
+            dot: snap.transport_dot,
+            doh: snap.transport_doh,
+        },
         cache: CacheStats {
             entries: cache_len,
             max_entries: cache_max,