fix: strip ANSI from TUI test frames so FORCE_COLOR cannot break assertions (#2207)

Ink writes styling as escape sequences inside the styled run, so an
accelerator underline splits the word it decorates: `<Text underline>I</Text>nfo`
reaches the frame buffer with escapes between `I` and `nfo`, and a plain
`toContain("Info")` fails against a component that is rendering correctly.
Chalk only emits color when it detects a TTY, so CI stays green and the six
failures land only on a developer whose shell exports FORCE_COLOR.

Add `__tests__/helpers/renderTui.tsx` — ink-testing-library's `render` with
`lastFrame()` and `frames` ANSI-stripped — and point all 16 renderer test
files at it. `frames` is a getter reading through to the live array, since
Ink appends to it as the component re-renders; the raw bytes stay reachable
as `stdout.lastFrame()`.

Pinning FORCE_COLOR=0 would turn the six green while hiding the class: any
future assertion on styled text has the same problem, and the suite would
stop covering the styled path at all.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MFp2LVH7UJST5i8bDBJghw
Signed-off-by: cliffhall <cliff@futurescale.com>

clients/tui/__tests__/PromptTestModal.test.tsx

@@ -1,6 +1,6 @@
 import React from "react";
 import { describe, it, expect, vi, afterEach } from "vitest";
-import { render } from "ink-testing-library";
+import { render } from "./helpers/renderTui";
 import type { InspectorClient } from "@inspector/core/mcp/index.js";
 import { AuthRecoveryRequiredError } from "@inspector/core/auth/challenge.js";
 import type { Prompt } from "@modelcontextprotocol/client";