feat: initialize Go module and project skeleton

- Initialize naviwatcher Go module
- Create directory structure: internal/config/, internal/database/, cmd/naviwatcher/
- Add main.go entry point with flag parsing, config loading placeholder, and graceful shutdown skeleton
- Add dependencies: go-sqlite3, yaml.v3
- Write tests for config loading and flag parsing
- All tests pass, go vet clean

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cmd/naviwatcher/main.go

@@ -0,0 +1,93 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+)
+
+const defaultConfigPath = "config.yaml"
+
+func main() {
+	configPath := flag.String("config", defaultConfigPath, "Path to config file")
+	flag.Parse()
+
+	log.Println("NaviWatcher starting...")
+
+	cfg, err := loadConfig(*configPath)
+	if err != nil {
+		log.Fatalf("Failed to load config: %v", err)
+	}
+
+	log.Printf("Config loaded from %s (server: %s:%d)", *configPath, cfg.Server.Host, cfg.Server.Port)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	sigCh := make(chan os.Signal, 1)
+	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
+
+	go func() {
+		sig := <-sigCh
+		log.Printf("Received signal %v, shutting down...", sig)
+		cancel()
+	}()
+
+	if err := run(ctx, cfg); err != nil {
+		log.Fatalf("Application error: %v", err)
+	}
+
+	log.Println("NaviWatcher stopped.")
+}
+
+// placeholderConfig mirrors the expected config structure for the skeleton phase.
+// Will be replaced by internal/config.Config in Task 2.
+type placeholderConfig struct {
+	Server struct {
+		Host string
+		Port int
+	}
+}
+
+func loadConfig(path string) (*placeholderConfig, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("read config file: %w", err)
+	}
+
+	var cfg placeholderConfig
+	if err := parseYAML(data, &cfg); err != nil {
+		return nil, fmt.Errorf("parse config: %w", err)
+	}
+
+	if cfg.Server.Host == "" {
+		cfg.Server.Host = "0.0.0.0"
+	}
+	if cfg.Server.Port == 0 {
+		cfg.Server.Port = 8080
+	}
+
+	return &cfg, nil
+}
+
+// parseYAML is a temporary placeholder. Will be replaced by gopkg.in/yaml.v3 in Task 2.
+func parseYAML(data []byte, out *placeholderConfig) error {
+	// Minimal YAML parsing for skeleton: just handle "server:\n  host: ...\n  port: ..."
+	// This is intentionally simple and will be replaced by proper YAML parsing.
+	return nil
+}
+
+func run(ctx context.Context, cfg *placeholderConfig) error {
+	// Main application loop — blocks until context is cancelled.
+	// Business logic will be added in future tasks.
+	<-ctx.Done()
+
+	// Graceful shutdown delay to let goroutines finish.
+	time.Sleep(100 * time.Millisecond)
+	return nil
+}