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/api/router.go

@@ -0,0 +1,23 @@
+package api
+
+import (
+	"database/sql"
+	"encoding/json"
+	"net/http"
+
+	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi/v5/middleware"
+)
+
+func NewRouter(db *sql.DB) http.Handler {
+	r := chi.NewRouter()
+	r.Use(middleware.Logger)
+	r.Use(middleware.Recoverer)
+
+	r.Get("/healthz", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(map[string]string{"status": "ok"})
+	})
+
+	return r
+}