refactor: eliminate code duplication - extract helpers and use retry utils

Extracted duplicate code and unified timeout handling across the codebase.

Changes:
- Extracted open_chat_and_load_data() function (eliminates 52 lines of duplication)
- Replaced manual y/н/Enter handling with handle_yes_no() from modal_handler (2 places)
- Replaced 7 direct tokio::time::timeout calls with retry utils (auth, main_input, main)
- Added with_timeout_ignore() for non-critical operations
- Fixed modal_handler.rs bug: corrected Russian 'y' key (д → н)
- Removed unused imports in handlers/mod.rs and utils/mod.rs

Impact:
- main_input.rs: 1164 → 958 lines (-206 lines, -18%)
- Code duplication: 52 lines eliminated
- Direct timeout calls: 7 → 1 (-86%)
- DRY principle applied throughout

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/input/handlers/mod.rs

@@ -17,10 +17,10 @@ pub mod modal;
 pub mod profile;
 pub mod search;
 
-pub use chat_list::*;
+// pub use chat_list::*;  // Пока не используется
 pub use clipboard::*;
 pub use global::*;
-pub use messages::*;
-pub use modal::*;
-pub use profile::*;
-pub use search::*;
+// pub use messages::*;   // Пока не используется
+// pub use modal::*;      // Пока не используется
+pub use profile::get_available_actions_count;  // Используется в main_input
+// pub use search::*;     // Пока не используется