refactor: complete Phase 13 deep architecture refactoring (etaps 3-7)

Split monolithic files into modular architecture:
- ui/messages.rs (893→365 lines): extract modals/, compose_bar.rs
- tdlib/messages.rs (836→3 files): split into messages/mod, convert, operations
- config/mod.rs (642→3 files): extract validation.rs, loader.rs
- Code duplication cleanup: shared components, ~220 lines removed
- Documentation: PROJECT_STRUCTURE.md rewrite, 16 files got //! docs

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

src/input/handlers/mod.rs

@@ -22,3 +22,21 @@ pub mod search;
 pub use clipboard::*;
 pub use global::*;
 pub use profile::get_available_actions_count;
+
+use crate::app::App;
+use crate::tdlib::TdClientTrait;
+use crate::types::MessageId;
+
+/// Скроллит к сообщению по его ID в текущем чате
+pub fn scroll_to_message<T: TdClientTrait>(app: &mut App<T>, message_id: MessageId) {
+    let msg_index = app
+        .td_client
+        .current_chat_messages()
+        .iter()
+        .position(|m| m.id() == message_id);
+
+    if let Some(idx) = msg_index {
+        let total = app.td_client.current_chat_messages().len();
+        app.message_scroll_offset = total.saturating_sub(idx + 5);
+    }
+}