feat: scaffold claude_pipe — claude -p equivalente parseando la TUI

App que obtiene la respuesta de claude como dato parseando su TUI interactiva,
en lugar de usar claude -p. Compone tres funciones del registry:

- pty_capture_idle_go_infra: captura el render de la TUI via PTY headless.
- vt_render_go_tui: reconstruye el layout 2D como texto plano.
- parse_claude_tui_go_tui: extrae los turnos + la respuesta final.

Salida por defecto con el mismo shape que claude -p --output-format json.
Formatos: json, text, turns, screen. Validada end-to-end: el campo result
coincide exacto con claude -p nativo (PONG == PONG). e2e_checks deterministas
con un fake TUI (tests/fake_claude.sh) que no gasta llamadas reales.

Fase 1 (one-shot). El streaming incremental queda como fase 2.

tests/fake_claude.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+# Fake claude TUI used by claude_pipe's deterministic e2e checks.
+#
+# It does NOT talk to any model. It ignores stdin (the prompt claude_pipe types)
+# and prints a minimal screen that mimics the markers parse_claude_tui_go_tui
+# looks for: a "❯ " user line and a "● " assistant line. After printing it idles
+# briefly so the capture's idle-cutoff fires and the process exits cleanly.
+#
+# stty -echo is essential: claude_pipe types the prompt into the PTY, and a TTY
+# echoes input by default. The real claude TUI captures keystrokes into its own
+# widget instead of echoing them; this fake has no such widget, so without
+# disabling echo the typed prompt would leak onto the screen and pollute the
+# parsed answer. The real claude binary is unaffected by this.
+#
+# This lets us validate the full capture -> render -> parse pipeline without
+# spending a real claude call or depending on network/model output.
+
+stty -echo 2>/dev/null || true
+
+printf '\xe2\x9d\xaf test prompt\n\n'        # "❯ test prompt"
+printf '\xe2\x97\x8f RESPUESTA_FAKE_OK\n\n'  # "● RESPUESTA_FAKE_OK"
+sleep 2