feat(tui): removed cursor positioning and refactored TUI rendering with explicit env defaults

- Removed getCursorPosition() method from Component interface and implementations, eliminating hardware cursor positioning support.
- Changed PI_HARDWARE_CURSOR environment variable default from implicit true to explicit '1' with fallback pattern.
- Changed PI_CLEAR_ON_SHRINK environment variable default from implicit false to explicit '0' with fallback pattern.
- Added screen clearing on TUI startup to prevent shell prompts from bleeding into first rendered frame.
- Refactored full-render logic into reusable fullRender() helper function.

packages/coding-agent/src/modes/utils/ui-helpers.ts

@@ -204,13 +204,6 @@ export class UiHelpers {
 				// Render tool call components
 				for (const content of message.content) {
 					if (content.type !== "toolCall") {
-						// Text/thinking blocks between tool calls break read grouping
-						if (
-							(content.type === "text" && content.text?.trim()) ||
-							(content.type === "thinking" && (content as any).thinking?.trim())
-						) {
-							readGroup = null;
-						}
 						continue;
 					}