feat: implement Phase 11 — inline photo viewing with ratatui-image

Add feature-gated (`images`) inline photo support:
- New types: MediaInfo, PhotoInfo, PhotoDownloadState, ImagesConfig
- Media module: ImageCache (LRU filesystem cache), ImageRenderer (terminal protocol detection)
- Photo metadata extraction from TDLib MessagePhoto with download_file() API
- ViewImage command (v/м) to toggle photo expand/collapse in message selection
- Two-pass UI rendering: placeholder lines in message bubbles + StatefulImage overlay
- Collapse all expanded photos on Esc (exit selection mode)

Dependencies: ratatui-image 8.1, image 0.25 (optional, behind `images` feature flag)

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

tests/helpers/fake_tdclient.rs

@@ -51,6 +51,9 @@ pub struct FakeTdClient {
     // Update channel для симуляции событий
     pub update_tx: Arc<Mutex<Option<mpsc::UnboundedSender<TdUpdate>>>>,
     
+    // Скачанные файлы (file_id -> local_path)
+    pub downloaded_files: Arc<Mutex<HashMap<i32, String>>>,
+
     // Настройки поведения
     pub simulate_delays: bool,
     pub fail_next_operation: Arc<Mutex<bool>>,
@@ -121,6 +124,7 @@ impl Clone for FakeTdClient {
             viewed_messages: Arc::clone(&self.viewed_messages),
             chat_actions: Arc::clone(&self.chat_actions),
             pending_view_messages: Arc::clone(&self.pending_view_messages),
+            downloaded_files: Arc::clone(&self.downloaded_files),
             update_tx: Arc::clone(&self.update_tx),
             simulate_delays: self.simulate_delays,
             fail_next_operation: Arc::clone(&self.fail_next_operation),
@@ -154,6 +158,7 @@ impl FakeTdClient {
             viewed_messages: Arc::new(Mutex::new(vec![])),
             chat_actions: Arc::new(Mutex::new(vec![])),
             pending_view_messages: Arc::new(Mutex::new(vec![])),
+            downloaded_files: Arc::new(Mutex::new(HashMap::new())),
             update_tx: Arc::new(Mutex::new(None)),
             simulate_delays: false,
             fail_next_operation: Arc::new(Mutex::new(false)),
@@ -237,6 +242,12 @@ impl FakeTdClient {
         self
     }
     
+    /// Добавить скачанный файл (для mock download_file)
+    pub fn with_downloaded_file(self, file_id: i32, path: &str) -> Self {
+        self.downloaded_files.lock().unwrap().insert(file_id, path.to_string());
+        self
+    }
+
     /// Установить доступные реакции
     pub fn with_available_reactions(self, reactions: Vec<String>) -> Self {
         *self.available_reactions.lock().unwrap() = reactions;
@@ -587,6 +598,20 @@ impl FakeTdClient {
         Ok(())
     }
     
+    /// Скачать файл (mock)
+    pub async fn download_file(&self, file_id: i32) -> Result<String, String> {
+        if self.should_fail() {
+            return Err("Failed to download file".to_string());
+        }
+
+        self.downloaded_files
+            .lock()
+            .unwrap()
+            .get(&file_id)
+            .cloned()
+            .ok_or_else(|| format!("File {} not found", file_id))
+    }
+
     /// Получить информацию о профиле
     pub async fn get_profile_info(&self, chat_id: ChatId) -> Result<ProfileInfo, String> {
         if self.should_fail() {

tests/helpers/fake_tdclient_impl.rs

@@ -161,6 +161,11 @@ impl TdClientTrait for FakeTdClient {
         FakeTdClient::toggle_reaction(self, chat_id, message_id, reaction).await
     }
 
+    // ============ File methods ============
+    async fn download_file(&self, file_id: i32) -> Result<String, String> {
+        FakeTdClient::download_file(self, file_id).await
+    }
+
     // ============ Getters (immutable) ============
     fn client_id(&self) -> i32 {
         0 // Fake client ID