Move shared packages from internal/ to pkg/ for external imports

BREAKING: Import paths changed from:
  github.com/satgate-io/satgate/internal/proxy
to:
  github.com/satgate-io/satgate/pkg/proxy

This allows satgate-enterprise to import OSS core packages.
Go's internal/ visibility rules prevent cross-module imports.

Also aligned toolchain to go1.24.11

Author: wayne mattadeen

cmd/satgate/main.go

@@ -22,11 +22,11 @@ import (
 	"github.com/rs/zerolog"
 	"github.com/rs/zerolog/log"
 
-	"github.com/satgate-io/satgate/internal/config"
-	"github.com/satgate-io/satgate/internal/governance"
-	"github.com/satgate-io/satgate/internal/lightning"
-	"github.com/satgate-io/satgate/internal/macaroon"
-	"github.com/satgate-io/satgate/internal/proxy"
+	"github.com/satgate-io/satgate/pkg/config"
+	"github.com/satgate-io/satgate/pkg/governance"
+	"github.com/satgate-io/satgate/pkg/lightning"
+	"github.com/satgate-io/satgate/pkg/macaroon"
+	"github.com/satgate-io/satgate/pkg/proxy"
 )
 
 var (

go.mod

@@ -2,7 +2,7 @@ module github.com/satgate-io/satgate
 
 go 1.24.0
 
-toolchain go1.24.5
+toolchain go1.24.11
 
 require (
 	github.com/redis/go-redis/v9 v9.17.2