feat(agent): enhance input handling with multi-line support and keyboard shortcuts

- Add bracketed paste mode for proper multi-line paste handling
- Add multi-line cursor navigation (Up/Down arrows)
- Add keyboard shortcuts:
  - Ctrl+J / Shift+Enter / Alt+Enter: Insert newline
  - Ctrl+Shift+Backspace: Delete to line start
  - Ctrl+U: Clear entire input
  - Ctrl+W / Alt+Backspace: Delete word left
- Fix newline rendering in raw mode (\n -> \r\n)
- Fix Ctrl+C to properly exit when input is empty
- Fix diff confirmation UI terminal state after IDE response

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: 2 people

src/agent/session.rs

@@ -424,7 +424,7 @@ impl ChatSession {
                 }
                 Ok(trimmed.to_string())
             }
-            InputResult::Cancel => Ok("".to_string()),
+            InputResult::Cancel => Ok("exit".to_string()),  // Ctrl+C exits
             InputResult::Exit => Ok("exit".to_string()),
         }
     }

src/agent/ui/diff.rs

@@ -7,6 +7,7 @@
 //! in the IDE's native diff viewer for a better experience.
 
 use colored::Colorize;
+use crossterm::{cursor, execute, terminal};
 use inquire::ui::{Color, IndexPrefix, RenderConfig, StyleSheet, Styled};
 use similar::{ChangeTag, TextDiff};
 use std::io::{self, Write};
@@ -368,6 +369,17 @@ pub async fn confirm_file_write_with_ide(
                 let _ = cancel_tx.send(());
                 terminal_handle.abort();
 
+                // CRITICAL: Reset terminal state since abort() doesn't let inquire cleanup
+                // This prevents terminal corruption when rendering subsequent diffs
+                let _ = terminal::disable_raw_mode();
+                let _ = execute!(
+                    std::io::stdout(),
+                    cursor::Show,
+                    terminal::Clear(terminal::ClearType::FromCursorDown)
+                );
+                print!("\r");
+                let _ = std::io::stdout().flush();
+
                 match ide_result {
                     Ok(DiffResult::Accepted { content: _ }) => {
                         println!("\n{} Changes accepted in IDE", "✓".green());