feat: initial implementation of uptodownbot

Telegram bot for downloading media from any site using yt-dlp.
Supports audio/video/both, quality selection, language picker,
container format selection, playlist pagination, progress updates,
per-user quotas, user preferences, download history, cancel at any step,
polling and webhook modes, proxy support, and SQLite persistence.

internal/domain/sanitize_test.go

@@ -0,0 +1,26 @@
+package domain
+
+import "testing"
+
+func TestValidateURL(t *testing.T) {
+	tests := []struct {
+		input string
+		want  string
+		ok    bool
+	}{
+		{"https://www.youtube.com/watch?v=123", "https://www.youtube.com/watch?v=123", true},
+		{"http://example.com/video", "http://example.com/video", true},
+		{"https://vimeo.com/123456", "https://vimeo.com/123456", true},
+		{"https://www.pornhub.com/view_video.php?viewkey=123", "https://www.pornhub.com/view_video.php?viewkey=123", true},
+		{"", "", false},
+		{"not a url", "", false},
+		{"ftp://example.com", "", false},
+		{"  https://example.com  ", "https://example.com", true},
+	}
+	for _, tt := range tests {
+		got, ok := ValidateURL(tt.input)
+		if ok != tt.ok || (ok && got != tt.want) {
+			t.Errorf("ValidateURL(%q) = (%q, %v), want (%q, %v)", tt.input, got, ok, tt.want, tt.ok)
+		}
+	}
+}