feat: GeoIP-based geo detection + configurable rename template

- Add MaxMind GeoLite2-City mmdb auto-download and IP-based geo lookup
  (covers all 249 countries globally, replacing limited 8-country regex)
- Add RenameOptions with 5 toggleable fields (flag/alias/country/city/index)
  stored as rename_options_json on collections
- Collection rename pipeline uses DetectGeoWithServer(name, server) which
  tries GeoIP lookup first, falls back to name-based regex matching
- Chinese country/city names + emoji flag prefix
- Country-city dedup: skip city when it equals country (e.g. 香港/香港)
- URI fragment encoding: url.QueryEscape -> url.PathEscape (%20 not +)
- Egress cache key excludes name field so renamed nodes still match cache
- Frontend: 5 toggle buttons in collection edit form, default all on
- Migrations: 0004 (source alias + collection rename_enabled),
  0005 (collection rename_options_json)

cmd/server.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"os"
 	"os/signal"
+	"path/filepath"
 	"syscall"
 	"time"
 
@@ -16,6 +17,7 @@ import (
 
 	"github.com/peterqiu0516/sub-store/internal/config"
 	"github.com/peterqiu0516/sub-store/internal/database"
+	"github.com/peterqiu0516/sub-store/internal/geoip"
 	"github.com/peterqiu0516/sub-store/internal/handler"
 	"github.com/peterqiu0516/sub-store/internal/middleware"
 )
@@ -54,6 +56,24 @@ func RunServer(cfg *config.Config) error {
 		return err
 	}
 
+	// Ensure GeoIP database exists (download in background if missing)
+	mmdbPath := filepath.Join(filepath.Dir(cfg.Database.Path), "GeoLite2-City.mmdb")
+	geoip.SetMmdbPath(mmdbPath)
+	if _, err := os.Stat(mmdbPath); err != nil {
+		logrus.Info("GeoIP database not found, downloading in background...")
+		go func() {
+			if err := geoip.DownloadMmdb(mmdbPath); err != nil {
+				logrus.WithError(err).Warn("GeoIP download failed, name-based detection will be used as fallback")
+			} else {
+				logrus.Info("GeoIP database downloaded successfully")
+				// Reload the reader
+				geoip.SetMmdbPath(mmdbPath)
+			}
+		}()
+	} else {
+		logrus.Info("GeoIP database found")
+	}
+
 	return startFiber(cfg, db)
 }