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/test_data.rs

@@ -5,6 +5,7 @@ use tele_tui::tdlib::{ChatInfo, MessageInfo, ProfileInfo, ReplyInfo};
 use tele_tui::types::{ChatId, MessageId};
 
 /// Builder для создания тестового чата
+#[allow(dead_code)]
 pub struct TestChatBuilder {
     id: i64,
     title: String,
@@ -21,6 +22,7 @@ pub struct TestChatBuilder {
     draft_text: Option<String>,
 }
 
+#[allow(dead_code)]
 impl TestChatBuilder {
     pub fn new(title: &str, id: i64) -> Self {
         Self {
@@ -100,6 +102,7 @@ impl TestChatBuilder {
 }
 
 /// Builder для создания тестового сообщения
+#[allow(dead_code)]
 pub struct TestMessageBuilder {
     id: i64,
     sender_name: String,
@@ -118,6 +121,7 @@ pub struct TestMessageBuilder {
     media_album_id: i64,
 }
 
+#[allow(dead_code)]
 impl TestMessageBuilder {
     pub fn new(content: &str, id: i64) -> Self {
         Self {