Refactor TUI components into separate files

- Move TUI components into src/tui/ folder
- Split out CustomEditor, StreamingMessageComponent, ToolExecutionComponent, FooterComponent
- Trim assistant message text content
- Add newline after per-message token/cost stats
- Improve code organization and maintainability

packages/coding-agent/src/tui/custom-editor.ts

@@ -0,0 +1,27 @@
+import { Editor } from "@mariozechner/pi-tui";
+
+/**
+ * Custom editor that handles Escape and Ctrl+C keys for coding-agent
+ */
+export class CustomEditor extends Editor {
+	public onEscape?: () => void;
+	public onCtrlC?: () => void;
+
+	handleInput(data: string): void {
+		// Intercept Escape key - but only if autocomplete is NOT active
+		// (let parent handle escape for autocomplete cancellation)
+		if (data === "\x1b" && this.onEscape && !this.isShowingAutocomplete()) {
+			this.onEscape();
+			return;
+		}
+
+		// Intercept Ctrl+C
+		if (data === "\x03" && this.onCtrlC) {
+			this.onCtrlC();
+			return;
+		}
+
+		// Pass to parent for normal handling
+		super.handleInput(data);
+	}
+}