docs: manual de producción completo + ajustes seed fallback

- Add production manual (docs/MANUAL_PRODUCCION.md)
- Fix seed script to work without OpenAI API key (zero-vector fallback)
- Fix alembic env to use database_url_str
- Fix pyproject.toml hatch build config

pyproject.toml

@@ -63,6 +63,9 @@ dev = [
 requires = ["hatchling"]
 build-backend = "hatchling.build"
 
+[tool.hatch.build.targets.wheel]
+packages = ["src"]
+
 [tool.ruff]
 target-version = "py312"
 line-length = 100