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/pages/1_🏛️_Registro.py

@@ -0,0 +1,60 @@
+"""Página de registro de agentes: lista, detalle, versiones y diff."""
+
+from __future__ import annotations
+
+import streamlit as st
+
+from agentforge_dashboard.client import CoreClient
+from agentforge_dashboard.components.diff_view import render_unified_diff
+
+
+@st.cache_resource
+def get_client() -> CoreClient:
+    return CoreClient()
+
+
+client = get_client()
+st.title("🏛️ Registro de Agentes")
+st.caption("Catálogo central de agentes con versionado tipo Git.")
+
+agents = client.list_agents()
+if not agents:
+    st.warning("No hay agentes registrados. Coloca YAMLs bajo `agents/<name>/`.")
+    st.stop()
+
+names = [a["name"] for a in agents]
+selected_name = st.selectbox("Agente", names)
+agent = client.get_agent(selected_name)
+
+col1, col2 = st.columns([2, 1])
+with col1:
+    st.subheader(f"{agent['name']} @ {agent['version']}")
+    st.write(f"**Estado:** `{agent['state']}`  |  **Owner:** {agent['owner']}")
+    st.write(f"**Propósito:** {agent['purpose']}")
+    st.write(f"**Guardrails activos:** {', '.join(agent['guardrails'])}")
+    st.write(f"**Threshold HITL:** risk_score ≥ {agent['risk_threshold_for_hitl']}")
+    with st.expander("System prompt"):
+        st.code(agent["system_prompt"], language="markdown")
+    with st.expander("Output schema"):
+        st.json(agent["output_schema"])
+
+with col2:
+    st.subheader("LLM")
+    st.json(agent["llm"])
+
+st.divider()
+st.subheader("Historial de versiones")
+versions = client.list_versions(selected_name)
+st.dataframe(versions, hide_index=True, use_container_width=True)
+
+if len(versions) >= 2:
+    st.subheader("Comparar versiones")
+    ids = [v["id"] for v in versions]
+    cf, ct = st.columns(2)
+    with cf:
+        v_from = st.selectbox("Desde", ids, index=0)
+    with ct:
+        v_to = st.selectbox("Hasta", ids, index=len(ids) - 1)
+    if v_from != v_to:
+        diff = client.diff_versions(selected_name, v_from, v_to)
+        render_unified_diff(diff["unified_diff"])