fix(tui): harden Terminal.app render behavior

Avoid Terminal.app paint corruption by disabling fast-echo in that terminal, sanitizing non-SGR control sequences before ANSI rendering, and defaulting Apple Terminal back to the safer 256-color path unless truecolor is explicitly requested.

ui-tui/src/__tests__/textInputFastEcho.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from 'vitest'
 
-import { canFastAppendShape, canFastBackspaceShape } from '../components/textInput.js'
+import { canFastAppendShape, canFastBackspaceShape, supportsFastEchoTerminal } from '../components/textInput.js'
 
 // The fast-echo path bypasses Ink and writes characters directly to stdout
 // for the common case of typing plain English at the end of the line. These
@@ -172,3 +172,14 @@ describe('canFastBackspaceShape', () => {
     expect(canFastBackspaceShape('hello ', 'hello '.length)).toBe(true)
   })
 })
+
+describe('supportsFastEchoTerminal', () => {
+  it('disables fast-echo in Apple Terminal', () => {
+    expect(supportsFastEchoTerminal({ TERM_PROGRAM: 'Apple_Terminal' } as NodeJS.ProcessEnv)).toBe(false)
+  })
+
+  it('keeps fast-echo enabled in VS Code and unknown terminals', () => {
+    expect(supportsFastEchoTerminal({ TERM_PROGRAM: 'vscode' } as NodeJS.ProcessEnv)).toBe(true)
+    expect(supportsFastEchoTerminal({ TERM: 'xterm-256color' } as NodeJS.ProcessEnv)).toBe(true)
+  })
+})