fix: unify DATA_DIR default to /var/lib/webhooker for all environments

Remove devDataDir() XDG-based logic. Both dev and prod now default
DATA_DIR to /var/lib/webhooker. Update Dockerfile and README to match.

internal/config/config_test.go

@@ -2,7 +2,6 @@ package config
 
 import (
 	"os"
-	"path/filepath"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -106,53 +105,38 @@ func TestEnvironmentConfig(t *testing.T) {
 	}
 }
 
-func TestDevDataDir(t *testing.T) {
-	t.Run("uses XDG_DATA_HOME when set", func(t *testing.T) {
-		os.Setenv("XDG_DATA_HOME", "/custom/data")
-		defer os.Unsetenv("XDG_DATA_HOME")
+func TestDefaultDataDir(t *testing.T) {
+	// Verify that when DATA_DIR is unset, the default is /var/lib/webhooker
+	// regardless of the environment setting.
+	for _, env := range []string{"", "dev", "prod"} {
+		name := env
+		if name == "" {
+			name = "unset"
+		}
+		t.Run("env="+name, func(t *testing.T) {
+			if env != "" {
+				os.Setenv("WEBHOOKER_ENVIRONMENT", env)
+				defer os.Unsetenv("WEBHOOKER_ENVIRONMENT")
+			} else {
+				os.Unsetenv("WEBHOOKER_ENVIRONMENT")
+			}
+			os.Unsetenv("DATA_DIR")
 
-		got := devDataDir()
-		assert.Equal(t, "/custom/data/webhooker", got)
-	})
+			var cfg *Config
+			app := fxtest.New(
+				t,
+				fx.Provide(
+					globals.New,
+					logger.New,
+					New,
+				),
+				fx.Populate(&cfg),
+			)
+			require.NoError(t, app.Err())
+			app.RequireStart()
+			defer app.RequireStop()
 
-	t.Run("falls back to HOME/.local/share/webhooker", func(t *testing.T) {
-		os.Unsetenv("XDG_DATA_HOME")
-
-		home, err := os.UserHomeDir()
-		require.NoError(t, err)
-
-		got := devDataDir()
-		assert.Equal(t, filepath.Join(home, ".local", "share", "webhooker"), got)
-	})
-
-	t.Run("result is always absolute", func(t *testing.T) {
-		os.Unsetenv("XDG_DATA_HOME")
-
-		got := devDataDir()
-		assert.True(t, filepath.IsAbs(got), "devDataDir() returned relative path: %s", got)
-	})
-}
-
-func TestDevDefaultDataDirIsAbsolute(t *testing.T) {
-	// Verify that when WEBHOOKER_ENVIRONMENT=dev and DATA_DIR is unset,
-	// the resulting DataDir is an absolute path.
-	os.Unsetenv("WEBHOOKER_ENVIRONMENT")
-	os.Unsetenv("DATA_DIR")
-
-	var cfg *Config
-	app := fxtest.New(
-		t,
-		fx.Provide(
-			globals.New,
-			logger.New,
-			New,
-		),
-		fx.Populate(&cfg),
-	)
-	require.NoError(t, app.Err())
-	app.RequireStart()
-	defer app.RequireStop()
-
-	assert.True(t, filepath.IsAbs(cfg.DataDir),
-		"dev default DataDir should be absolute, got: %s", cfg.DataDir)
+			assert.Equal(t, "/var/lib/webhooker", cfg.DataDir)
+		})
+	}
 }