Add custom logger with source location tracking and remove verbose database logs

- Create internal/logger package with Logger wrapper around slog
- Logger automatically adds source file, line number, and function name to all log entries
- Use golang.org/x/term to properly detect if stdout is a terminal
- Replace all slog.Logger usage with logger.Logger throughout the codebase
- Remove verbose logging from database GetStats() method
- Update all constructors and dependencies to use the new logger

internal/routewatch/app_test.go

@@ -1,12 +1,3 @@
 package routewatch
 
-import (
-	"testing"
-)
-
-func TestNewLogger(t *testing.T) {
-	logger := NewLogger()
-	if logger == nil {
-		t.Fatal("NewLogger returned nil")
-	}
-}
+// Tests for routewatch package are in app_integration_test.go