feat(dashboard): página de Registro con detalle, versiones y diff coloreado

- components/diff_view.render_unified_diff: pinta +/-/@@ del unified diff.
- pages/1_🏛️_Registro.py: selector de agente, detalle (estado, owner, propósito,
  guardrails, system_prompt, output_schema, llm), tabla de versiones y comparador.
- pyproject: per-file-ignore N999 en pages/* — Streamlit exige nombres
  "<n>_<emoji>_<Label>.py" para la navegación multipágina.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

dashboard/src/agentforge_dashboard/components/diff_view.py

@@ -0,0 +1,26 @@
+"""Componente para renderizar diffs unificados con coloreado básico."""
+
+from __future__ import annotations
+
+import streamlit as st
+
+
+def render_unified_diff(diff_text: str) -> None:
+    if not diff_text.strip():
+        st.info("Sin diferencias entre las versiones seleccionadas.")
+        return
+    lines: list[str] = []
+    for line in diff_text.splitlines():
+        if line.startswith("+") and not line.startswith("+++"):
+            lines.append(f'<span style="color:#22c55e">{line}</span>')
+        elif line.startswith("-") and not line.startswith("---"):
+            lines.append(f'<span style="color:#ef4444">{line}</span>')
+        elif line.startswith("@@"):
+            lines.append(f'<span style="color:#3b82f6;font-weight:bold">{line}</span>')
+        else:
+            lines.append(line)
+    html = (
+        "<pre style='background:#0f172a;color:#e2e8f0;padding:12px;border-radius:6px;"
+        "font-size:12px;overflow:auto'>" + "\n".join(lines) + "</pre>"
+    )
+    st.markdown(html, unsafe_allow_html=True)