Add systemd unit, use favicon as navbar logo, collapse ASPA explainer under API
- aspa.service.example: hardened unit for running the binary bare-metal (DynamicUser, ProtectSystem=strict, etc.), documented in the README
- base.html: navbar brand mark now renders the same inline SVG as the favicon instead of a plain gradient box; also added logo.png at repo root rasterized from the same SVG
- lookup.html: JSON API card now comes first, with "What is ASPA?"
nested inside it as a collapsed section
Co-Authored-By: Claude Sonnet 5 noreply@anthropic.com Claude-Session: https://claude.ai/code/session_01SdWQ3jVyzwRoQjVfAfK4mZ