Fix TUI apps (mc, htop, vim) freezing in SSH terminal

- Remove LNM mode that corrupted cursor positioning for TUI programs
- Add render debouncing (~60fps) to prevent UI thread blocking
- Add data batching in terminal tab to reduce render calls
- Increase SSH recv buffer from 4KB to 64KB

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

gui/tabs/terminal_tab.py

@@ -30,6 +30,10 @@ class TerminalTab(ctk.CTkFrame):
         self._terminal.pack(fill="both", expand=True, padx=5, pady=5)
         self._terminal.set_status(t("term_disconnected"), "#888888")
 
+        # Data batching buffer
+        self._data_buffer = bytearray()
+        self._flush_after_id = None
+
     def set_server(self, alias: str | None):
         if alias == self._current_alias:
             return
@@ -84,7 +88,16 @@ class TerminalTab(ctk.CTkFrame):
             self._session = None
 
     def _on_data_received(self, data: bytes):
-        self.after(0, lambda d=data: self._terminal.feed(d))
+        self._data_buffer.extend(data)
+        if self._flush_after_id is None:
+            self._flush_after_id = self.after(8, self._flush_data_buffer)
+
+    def _flush_data_buffer(self):
+        self._flush_after_id = None
+        if self._data_buffer:
+            chunk = bytes(self._data_buffer)
+            self._data_buffer.clear()
+            self._terminal.feed(chunk)
 
     def _on_disconnected(self):
         if self._intentional_disconnect: