fix: lifecycle-safe logger teardown without global state

Store file handle per module, swap lifecycle logger before closing file,
return teardown errors, remove duplicate Module() func.

Co-authored-by: Cursor <cursoragent@cursor.com>

module.go

@@ -0,0 +1,51 @@
+package applog
+
+import (
+	"io"
+	"log/slog"
+
+	"gitea.auvem.com/go-toolkit/app"
+)
+
+// ModuleName is the name of the module provided by applog.
+const ModuleName = "app logger"
+
+// AppLogOpts contains options for configuring the application logger.
+type AppLogOpts struct {
+	// ConsoleOutput is the writer for pretty-printed console logs. If nil,
+	// console output is disabled. Generally recommended to set this to
+	// os.Stderr, leaving os.Stdout for application output (usually via
+	// fmt.Print*).
+	ConsoleOutput io.Writer
+
+	// ConsoleLevel is the minimum log level for console output. Defaults to
+	// slog.LevelInfo when console output is enabled.
+	ConsoleLevel slog.Level
+
+	// FileOutput is the path to a file where JSON formatted logs will be
+	// written. If empty, file output is disabled.
+	FileOutput string
+
+	// FileLevel is the minimum log level for file output. Defaults to
+	// slog.LevelInfo when file output is enabled.
+	FileLevel slog.Level
+
+	// SetDefault sets slog.SetDefault to the configured logger.
+	SetDefault bool
+
+	// DisableAnnouncement skips the startup log line after initialization.
+	DisableAnnouncement bool
+}
+
+// Module returns an app module that configures slog for the lifecycle.
+func (opts AppLogOpts) Module() *app.Module {
+	state := &moduleState{opts: opts}
+	return app.NewModule(ModuleName, app.ModuleOpts{
+		Setup: func(m *app.Module) error {
+			return state.setup(m)
+		},
+		Teardown: func(m *app.Module) error {
+			return state.teardown(m.Lifecycle())
+		},
+	})
+}