v0.22.0: lookup on youtube

Right-click a song -> "lookup on youtube" opens a YouTube search for
"<title> <artist>" in the default browser. Single selection only.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/test_round58.py

@@ -0,0 +1,38 @@
+"""Round 58: "lookup on youtube" in a song's right-click menu.
+
+The URL is built by a pure helper so the query encoding can be checked
+without opening a browser.
+"""
+
+from PyQt6.QtCore import QUrl, QUrlQuery
+
+from lintunes.models import Track
+from lintunes.gui.track_table import youtube_search_url
+
+
+def _query(url):
+    return QUrlQuery(url).queryItemValue(
+        "search_query", QUrl.ComponentFormattingOption.FullyDecoded)
+
+
+def test_title_then_artist(qapp):
+    url = youtube_search_url(Track(track_id=1, name="I Know", artist="Dionne Farris"))
+    assert url.scheme() == "https"
+    assert url.host() == "www.youtube.com"
+    assert url.path() == "/results"
+    assert _query(url) == "I Know Dionne Farris"
+
+
+def test_special_characters_survive(qapp):
+    track = Track(track_id=1, name="Rock & Roll #9 ✨", artist="Beyoncé")
+    url = youtube_search_url(track)
+    assert _query(url) == "Rock & Roll #9 ✨ Beyoncé"
+    encoded = url.toString(QUrl.ComponentFormattingOption.FullyEncoded)
+    assert "&" not in encoded.split("search_query=", 1)[1]
+    assert "#" not in encoded
+
+
+def test_missing_artist_has_no_trailing_space(qapp):
+    url = youtube_search_url(Track(track_id=1, name="Zuuso"))
+    assert _query(url) == "Zuuso"
+