Introduce a Helm-chart-like template system for MCP servers. Templates are
YAML files in templates/ that get seeded into the DB on startup. Users can
browse them with `mcpctl get templates`, inspect with `mcpctl describe
template`, and instantiate with `mcpctl create server --from-template=`.
Also adds Portainer deployment scripts, mcplocal systemd service,
Streamable HTTP MCP endpoint, and RPM packaging for mcpctl-local.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
