Enhance TUI: add paste event handling, integrate bracketed paste mode, and implement paste support in editing mode.

Fixes #20

crates/owlen-tui/src/chat_app.rs

@@ -381,6 +381,24 @@ impl ChatApp {
             Event::Tick => {
                 // Future: update streaming timers
             }
+            Event::Paste(text) => {
+                // Handle paste events - insert text directly without triggering sends
+                if matches!(self.mode, InputMode::Editing) {
+                    // In editing mode, insert the pasted text directly into textarea
+                    let lines: Vec<&str> = text.lines().collect();
+                    for (i, line) in lines.iter().enumerate() {
+                        for ch in line.chars() {
+                            self.textarea.insert_char(ch);
+                        }
+                        // Insert newline between lines (but not after the last line)
+                        if i < lines.len() - 1 {
+                            self.textarea.insert_newline();
+                        }
+                    }
+                    self.sync_textarea_to_buffer();
+                }
+                // Ignore paste events in other modes
+            }
             Event::Key(key) => match self.mode {
                 InputMode::Normal => {
                     // Handle multi-key sequences first