feat(geoip): country-code enrichment via RIR delegated-stats

Populates Attacker.country_code + country_source (MVP) using the five
RIR delegated-stats files (ARIN/RIPE/APNIC/LACNIC/AFRINIC). Offline,
license-free, no outbound traffic that could burn honeypot stealth.

- decnet.geoip package with factory/base/lookup + rir/ subpackage
  (fetch/parse/provider) mirroring the db + bus factory convention
- Profiler._build_record calls enrich_ip on every upsert
- Idempotent ALTER TABLE migrations for both SQLite and MySQL
- decnet geoip refresh/lookup CLI (master-only)
- /var/lib/decnet/geoip seeded by decnet init
- DECNET_GEOIP_ENABLED=false kill-switch; set in tests/conftest.py so
  unit tests never trigger the first-access fetch

decnet/geoip/rir/__init__.py

@@ -0,0 +1,9 @@
+"""RIR delegated-stats provider.
+
+Free, offline, no license: each Regional Internet Registry publishes a
+daily plaintext file mapping IPv4 allocations to countries. Together the
+five RIR files cover the entire assigned IPv4 space.
+
+Direct imports of :class:`RirProvider` are discouraged — go through
+:func:`decnet.geoip.factory.get_provider`.
+"""