Improve OAuth login UI with consistent dialog component

- Add LoginDialogComponent with proper borders (top/bottom DynamicBorder)
- Refactor all OAuth providers to use racing approach (browser callback vs manual paste)
- Add onEscape handler to Input component for cancellation
- Add abortable sleep for GitHub Copilot polling (instant cancel on Escape)
- Show OS-specific click hint (Cmd+click on macOS, Ctrl+click elsewhere)
- Clear content between login phases (fixes GitHub Copilot two-phase flow)
- Use InteractiveMode's showStatus/showError for result messages
- Reorder providers: Anthropic, ChatGPT, GitHub Copilot, Gemini CLI, Antigravity

packages/tui/src/components/input.ts

@@ -11,6 +11,7 @@ export class Input implements Component {
 	private value: string = "";
 	private cursor: number = 0; // Cursor position in the value
 	public onSubmit?: (value: string) => void;
+	public onEscape?: () => void;
 
 	// Bracketed paste mode buffering
 	private pasteBuffer: string = "";
@@ -64,6 +65,12 @@ export class Input implements Component {
 		}
 		const kb = getEditorKeybindings();
 
+		// Escape/Cancel
+		if (kb.matches(data, "selectCancel")) {
+			if (this.onEscape) this.onEscape();
+			return;
+		}
+
 		// Submit
 		if (kb.matches(data, "submit") || data === "\n") {
 			if (this.onSubmit) this.onSubmit(this.value);