fix: resolve all 40 clippy warnings (dead_code, unused_imports, lints)

- Add #[allow(unused_imports)] on pub re-exports used only by lib/tests
- Add #[allow(dead_code)] on public API items unused in binary target
- Fix collapsible_if, redundant_closure, unnecessary_map_or in main.rs
- Prefix unused test variables with underscore

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/helpers/fake_tdclient.rs

@@ -9,6 +9,7 @@ use tokio::sync::mpsc;
 
 /// Update события от TDLib (упрощённая версия)
 #[derive(Debug, Clone)]
+#[allow(dead_code)]
 pub enum TdUpdate {
     NewMessage {
         chat_id: ChatId,
@@ -47,6 +48,7 @@ pub enum TdUpdate {
 }
 
 /// Упрощённый mock TDLib клиента для тестов
+#[allow(dead_code)]
 pub struct FakeTdClient {
     // Данные
     pub chats: Arc<Mutex<Vec<ChatInfo>>>,
@@ -86,6 +88,7 @@ pub struct FakeTdClient {
 }
 
 #[derive(Debug, Clone)]
+#[allow(dead_code)]
 pub struct SentMessage {
     pub chat_id: i64,
     pub text: String,
@@ -94,6 +97,7 @@ pub struct SentMessage {
 }
 
 #[derive(Debug, Clone)]
+#[allow(dead_code)]
 pub struct EditedMessage {
     pub chat_id: i64,
     pub message_id: MessageId,
@@ -101,6 +105,7 @@ pub struct EditedMessage {
 }
 
 #[derive(Debug, Clone)]
+#[allow(dead_code)]
 pub struct DeletedMessages {
     pub chat_id: i64,
     pub message_ids: Vec<MessageId>,
@@ -108,6 +113,7 @@ pub struct DeletedMessages {
 }
 
 #[derive(Debug, Clone)]
+#[allow(dead_code)]
 pub struct ForwardedMessages {
     pub from_chat_id: i64,
     pub to_chat_id: i64,
@@ -115,6 +121,7 @@ pub struct ForwardedMessages {
 }
 
 #[derive(Debug, Clone)]
+#[allow(dead_code)]
 pub struct SearchQuery {
     pub chat_id: i64,
     pub query: String,
@@ -158,6 +165,7 @@ impl Clone for FakeTdClient {
     }
 }
 
+#[allow(dead_code)]
 impl FakeTdClient {
     pub fn new() -> Self {
         Self {