Add DuckDuckGo support and refactor caching system

Introduced DuckDuckGo as a new search provider alongside Google. Implemented a flexible caching system with in-memory, file-based, and no-op cache options to improve modularity. Updated dependencies and revised the project structure for improved maintainability.

cmd/answer.go

@@ -5,13 +5,15 @@ import (
 	"answer/pkg/cache"
 	"answer/pkg/search"
 	"context"
-	gollm "gitea.stevedudenhoeffer.com/steve/go-llm"
-	"github.com/joho/godotenv"
-	"github.com/urfave/cli"
 	"log/slog"
 	"os"
 	"strings"
 	"time"
+
+	"github.com/joho/godotenv"
+	"github.com/urfave/cli"
+
+	gollm "gitea.stevedudenhoeffer.com/steve/go-llm"
 )
 
 func getKey(key string, env string) string {
@@ -57,13 +59,13 @@ func main() {
 
 			&cli.StringFlag{
 				Name:  "search-provider",
-				Value: "google",
+				Value: "duckduckgo",
 				Usage: "search provider to use for searching the web",
 			},
 
 			&cli.StringFlag{
 				Name:  "cache-provider",
-				Value: "memory",
+				Value: "file",
 				Usage: "cache provider to use for caching search results",
 			},
 		},
@@ -111,6 +113,13 @@ func main() {
 			case "google":
 				question.Search = search.Google{Cache: question.Cache}
 
+			case "duckduckgo":
+				var err error
+				question.Search, err = search.NewDuckDuckGo(question.Cache)
+				if err != nil {
+					panic("failed to create duckduckgo search: " + err.Error())
+				}
+
 			default:
 				panic("unknown search provider")
 			}