build: añade Dockerfiles para core y dashboard con healthchecks y usuario no-root

- core/Dockerfile: python:3.11-slim, instala requirements + modelo spaCy
  (en_core_web_sm para Presidio), corre como usuario `agent`, HEALTHCHECK sobre
  /health, CMD uvicorn :8000.
- dashboard/Dockerfile: python:3.11-slim, usuario `dash`, HEALTHCHECK sobre
  /_stcore/health, CMD streamlit :8501 headless.
- .dockerignore: excluye venv, caches, datos runtime, .env, specs/plans y tests.

Ambos pasan `docker build --check` sin warnings.

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

dashboard/Dockerfile

@@ -0,0 +1,31 @@
+# syntax=docker/dockerfile:1.7
+
+FROM python:3.11-slim
+
+ENV PYTHONUNBUFFERED=1 \
+    PYTHONDONTWRITEBYTECODE=1 \
+    PIP_NO_CACHE_DIR=1
+
+WORKDIR /app
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    curl \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY dashboard/requirements.txt /app/requirements.txt
+RUN pip install -r /app/requirements.txt
+
+COPY dashboard/src /app/src
+ENV PYTHONPATH=/app/src
+
+RUN useradd --create-home --shell /bin/bash dash && chown -R dash:dash /app
+USER dash
+
+EXPOSE 8501
+
+HEALTHCHECK --interval=10s --timeout=3s --start-period=10s --retries=3 \
+    CMD curl -fsS http://localhost:8501/_stcore/health || exit 1
+
+CMD ["streamlit", "run", "/app/src/agentforge_dashboard/app.py", \
+     "--server.address=0.0.0.0", "--server.port=8501", \
+     "--server.headless=true", "--browser.gatherUsageStats=false"]