Add GeoIP country detection with flag emoji remarks and per-country subscription files

- Add GeoSettings config (ip-api.com batch API with rate limiting)
- Create src/geoip.go: DNS resolution cache, batch GeoIP lookup, country-to-flag emoji conversion
- Replace @DeltaKroneckerGithub remark with country flag emoji (e.g. US, DE)
- Write per-country subscription files (config/countries/{cc}.txt and .yaml)
- Add 'By Country' table to README with links to per-country files
- Configs that fail GeoIP lookup fall back to default remark

Author: Delta-Kronecker

data/settings.json

@@ -44,5 +44,12 @@
     "config_name": "proxy",
     "main_file": "config/all_configs.txt",
     "protocols_dir": "config/protocols"
+  },
+  "geo": {
+    "api_url": "http://ip-api.com/batch",
+    "timeout_ms": 5000,
+    "max_retries": 2,
+    "batch_size": 100,
+    "batch_delay_ms": 1200
   }
 }