Simplify log source to file.go:line format

Replace verbose source object with simple "file.go:line" string
for cleaner log output.

internal/logger/logger.go

@@ -2,8 +2,10 @@
 package logger
 
 import (
+	"fmt"
 	"log/slog"
 	"os"
+	"path/filepath"
 	"runtime"
 
 	"go.uber.org/fx"
@@ -37,18 +39,30 @@ func New(_ fx.Lifecycle, params Params) (*Logger, error) {
 		tty = true
 	}
 
+	// replaceAttr simplifies the source attribute to "file.go:line"
+	replaceAttr := func(groups []string, a slog.Attr) slog.Attr {
+		if a.Key == slog.SourceKey {
+			if src, ok := a.Value.Any().(*slog.Source); ok {
+				a.Value = slog.StringValue(fmt.Sprintf("%s:%d", filepath.Base(src.File), src.Line))
+			}
+		}
+		return a
+	}
+
 	var handler slog.Handler
 	if tty {
 		// Text output for development
 		handler = slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{
-			Level:     l.level,
-			AddSource: true,
+			Level:       l.level,
+			AddSource:   true,
+			ReplaceAttr: replaceAttr,
 		})
 	} else {
 		// JSON output for production
 		handler = slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{
-			Level:     l.level,
-			AddSource: true,
+			Level:       l.level,
+			AddSource:   true,
+			ReplaceAttr: replaceAttr,
 		})
 	}