Add IP-to-country geolocation service

Introduce a geoloc package that stores CIDR-to-country mappings in
PostgreSQL using the native cidr type with a GiST index for fast
containment lookups. Data comes from the ipverse/country-ip-blocks
dataset added as a git submodule.

A standalone geoloc-import command reads the TXT files from disk
and bulk-loads them via COPY. probod wires the service and logs a
warning when the table is empty.

Signed-off-by: Émile Ré <emile@getprobo.com>

cmd/geoloc-import/main.go

@@ -0,0 +1,104 @@
+// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+// Command geoloc-import loads IP-to-country CIDR blocks from the
+// ipverse/country-ip-blocks dataset into the common_ip_country_blocks table.
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"net/url"
+	"os"
+
+	"go.gearno.de/kit/pg"
+	"go.probo.inc/probo/pkg/geoloc"
+)
+
+func main() {
+	if err := run(); err != nil {
+		fmt.Fprintf(os.Stderr, "error: %v\n", err)
+		os.Exit(1)
+	}
+}
+
+func run() error {
+	var (
+		pgDSN   string
+		dataDir string
+	)
+
+	flag.StringVar(
+		&pgDSN,
+		"pg-dsn",
+		os.Getenv("DATABASE_URL"),
+		"PostgreSQL connection URL (default: DATABASE_URL env)",
+	)
+	flag.StringVar(
+		&dataDir,
+		"data-dir",
+		"pkg/geoloc/data/country-ip-blocks",
+		"path to ipverse country-ip-blocks checkout",
+	)
+	flag.Parse()
+
+	if pgDSN == "" {
+		return fmt.Errorf("set -pg-dsn or DATABASE_URL")
+	}
+
+	ctx := context.Background()
+
+	pgClient, err := newPgClientFromDSN(pgDSN)
+	if err != nil {
+		return fmt.Errorf("cannot create pg client: %w", err)
+	}
+
+	svc := geoloc.NewService(pgClient)
+
+	fmt.Printf("importing IP country blocks from %s\n", dataDir)
+
+	if err := svc.ImportFromDir(ctx, dataDir); err != nil {
+		return fmt.Errorf("cannot import geoloc data: %w", err)
+	}
+
+	fmt.Println("done")
+	return nil
+}
+
+func newPgClientFromDSN(dsn string) (*pg.Client, error) {
+	u, err := url.Parse(dsn)
+	if err != nil {
+		return nil, fmt.Errorf("cannot parse DSN: %w", err)
+	}
+
+	var opts []pg.Option
+
+	if u.Host != "" {
+		opts = append(opts, pg.WithAddr(u.Host))
+	}
+
+	if u.User != nil {
+		opts = append(opts, pg.WithUser(u.User.Username()))
+		if password, ok := u.User.Password(); ok {
+			opts = append(opts, pg.WithPassword(password))
+		}
+	}
+
+	if len(u.Path) > 1 {
+		opts = append(opts, pg.WithDatabase(u.Path[1:]))
+	}
+
+	return pg.NewClient(opts...)
+}