Stage 1: project skeleton, SQLite, migrations, HTTP server

- go mod init with chi, modernc.org/sqlite, golang.org/x/crypto
- Custom embedded migration runner (no CGO dependency)
- Config from TERDUT_ADDR / TERDUT_DB_PATH env vars
- chi router with /healthz endpoint
- Graceful shutdown on SIGINT/SIGTERM

internal/config/config.go

@@ -0,0 +1,20 @@
+package config
+
+import "os"
+
+type Config struct {
+	Addr   string
+	DBPath string
+}
+
+func Load() Config {
+	addr := os.Getenv("TERDUT_ADDR")
+	if addr == "" {
+		addr = ":8080"
+	}
+	dbPath := os.Getenv("TERDUT_DB_PATH")
+	if dbPath == "" {
+		dbPath = "terdut.db"
+	}
+	return Config{Addr: addr, DBPath: dbPath}
+}