Open more YouTube link types and playlists from links

Route YouTube search results links to search and nocookie embeds to the
video, match YouTube hosts exactly, and report YouTube pages without a
video as unsupported instead of sending them to yt-dlp. A watch link
inside a playlist shows both the video and the playlist when loaded, and
plays the video with the playlist queued around it. URL scheme play,
queue and bookmark actions accept playlist links.

YatteeTests/NavigationTests.swift

@@ -326,16 +326,59 @@ struct URLRouterTests {
         }
     }
 
-    @Test("YouTube URL without video ID routes to external video")
+    @Test("YouTube watch URL without video ID routes nowhere")
     func urlWithoutVideoID() {
         let url = URL(string: "https://www.youtube.com/watch")!
-        let destination = router.route(url)
-        // YouTube URLs without video ID are now treated as potential external videos
-        if case .externalVideo(let extractedURL) = destination {
-            #expect(extractedURL == url)
-        } else {
-            Issue.record("Expected externalVideo destination")
-        }
+        #expect(router.route(url) == nil)
+    }
+
+    @Test("YouTube pages without a video route nowhere instead of to yt-dlp", arguments: [
+        "https://www.youtube.com/",
+        "https://youtube.com",
+        "https://www.youtube.com/feed/subscriptions",
+        "https://www.youtube.com/hashtag/music",
+        "https://www.youtube.com/results",
+        "https://music.youtube.com/browse/MPREb_abc",
+    ])
+    func youTubeNonVideoPages(_ string: String) {
+        #expect(router.route(URL(string: string)!) == nil)
+    }
+
+    @Test("Other unparsed YouTube links still go to yt-dlp")
+    func youTubeClipGoesToExtraction() {
+        let url = URL(string: "https://www.youtube.com/clip/UgkxABC")!
+        #expect(router.route(url) == .externalVideo(url))
+    }
+
+    @Test("YouTube search results link routes to search")
+    func youTubeSearchLink() {
+        let url = URL(string: "https://www.youtube.com/results?search_query=swift+concurrency")!
+        #expect(router.route(url) == .search("swift concurrency"))
+    }
+
+    @Test("youtube-nocookie embed routes to video")
+    func youTubeNoCookieEmbed() {
+        let url = URL(string: "https://www.youtube-nocookie.com/embed/dQw4w9WgXcQ?start=30")!
+        #expect(router.route(url) == .video(.id(.global("dQw4w9WgXcQ"))))
+    }
+
+    @Test("Look-alike hosts are not YouTube")
+    func lookAlikeHosts() {
+        let url = URL(string: "https://notyoutube.com/watch?v=dQw4w9WgXcQ")!
+        #expect(router.route(url) == .externalVideo(url))
+        #expect(!router.isYouTubeHost("youtube.com.evil.example"))
+        #expect(router.isYouTubeHost("music.youtube.com"))
+    }
+
+    @Test("Watch link playlist context", arguments: [
+        ("https://www.youtube.com/watch?v=dQw4w9WgXcQ&list=PLtest123", "PLtest123"),
+        ("https://www.youtube.com/watch?v=dQw4w9WgXcQ&list=RDdQw4w9WgXcQ", nil),
+        ("https://www.youtube.com/watch?v=dQw4w9WgXcQ&list=WL", nil),
+        ("https://www.youtube.com/watch?v=dQw4w9WgXcQ", nil),
+        ("https://www.youtube.com/playlist?list=PLtest123", nil),
+    ] as [(String, String?)])
+    func playlistContext(_ string: String, _ expected: String?) {
+        #expect(router.youTubePlaylistContext(URL(string: string)!) == expected)
     }
 
     @Test("Known non-PeerTube hosts route to external video")