test: hardened new spinner and title-latch suites against full-suite pollution

- Exported stopSharedSpinnerTicker() and wired it into InteractiveMode.stop(): a live block missed by per-component stopAnimation kept the shared 80ms interval alive as a lingering event-loop handle; the spinner suite uses it to observe a freshly armed ticker instead of one leaked by earlier files
- Title-disposal tests now save/clear/restore PI_NO_TITLE (main() in ACP/RPC mode sets it process-wide), matching the prewarm and orphan-submit precedent

packages/coding-agent/test/modes/components/tool-execution-spinner.test.ts

@@ -1,7 +1,8 @@
-import { afterEach, beforeAll, describe, expect, it, vi } from "bun:test";
+import { afterEach, beforeAll, beforeEach, describe, expect, it, vi } from "bun:test";
 import { stripVTControlCharacters } from "node:util";
 import {
 	SPINNER_RENDER_INTERVAL_MS,
+	stopSharedSpinnerTicker,
 	ToolExecutionComponent,
 } from "@oh-my-pi/pi-coding-agent/modes/components/tool-execution";
 import { TranscriptContainer } from "@oh-my-pi/pi-coding-agent/modes/components/transcript-container";
@@ -17,6 +18,13 @@ describe("ToolExecutionComponent live preview spinners", () => {
 		await initTheme();
 	});
 
+	// Earlier test files may leak live blocks (components never stopAnimation'd),
+	// which keeps the shared ticker armed on a REAL interval and makes these
+	// fake-timer assertions observe a pre-existing timer instead of a fresh one.
+	beforeEach(() => {
+		stopSharedSpinnerTicker();
+	});
+
 	afterEach(() => {
 		vi.useRealTimers();
 		vi.restoreAllMocks();