Leave SIGINT and SIGTERM to fx (closes #131)

The start hook registered its own handler for SIGINT and SIGTERM and
asked fx to shut down from it, although fx already stops the daemon on
both signals. A stop signal was handled twice, and the handler stayed
registered after the stop. fx now handles both signals alone, as
GO_HTTP_SERVER_CONVENTIONS.md "Signal Handling and Graceful Shutdown"
requires.

Model: opus-5-5

internal/routewatch/cli.go

@@ -3,10 +3,8 @@ package routewatch
 import (
 	"context"
 	"os"
-	"os/signal"
 	"runtime"
 	"strings"
-	"syscall"
 	"time"
 
 	"git.eeqj.de/sneak/routewatch/internal/logger"
@@ -62,10 +60,10 @@ func logDebugStats(logger *logger.Logger) {
 }
 
 // CLIEntry is the main entry point for the routewatch command-line interface.
-// It initializes the application using the fx dependency injection framework,
-// sets up signal handling for graceful shutdown, and starts the RouteWatch
-// service. This function blocks until the application receives a shutdown
-// signal or encounters a fatal error.
+// It initializes the application using the fx dependency injection framework
+// and starts the RouteWatch service. It blocks until fx receives SIGINT or
+// SIGTERM or RouteWatch stops on an error; fx then runs the stop hook and sets
+// the exit code.
 func CLIEntry() {
 	app := fx.New(
 		fx.Options(getModule()...),
@@ -81,20 +79,6 @@ func CLIEntry() {
 					// Start debug stats logging
 					go logDebugStats(logger)
 
-					// Handle shutdown signals
-					sigCh := make(chan os.Signal, 1)
-					signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM)
-
-					go func() {
-						<-sigCh
-						logger.Info("Received shutdown signal")
-
-						err := shutdowner.Shutdown()
-						if err != nil {
-							logger.Error("Failed to shutdown gracefully", "error", err)
-						}
-					}()
-
 					go func() {
 						err := rw.Run(ctx)
 						if err != nil {