fix: _is_direct_url label-boundary host match (no notyoutube.com false positive)

Review finding: bare endswith routed look-alike hosts to the direct yt-dlp
path. Match on a domain-label boundary and drop the redundant _DIRECT_HOSTS.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_odesli.py

@@ -88,6 +88,20 @@ def test_is_direct_url_youtube_playlist_true():
     assert mf._is_direct_url("https://www.youtube.com/playlist?list=PLabc")
 
 
+def test_is_direct_url_lookalike_hosts_false():
+    # Trailing-substring look-alikes must NOT be treated as direct (label boundary).
+    assert not mf._is_direct_url("https://notyoutube.com/watch?v=abc")
+    assert not mf._is_direct_url("https://myyoutube.com/x")
+    assert not mf._is_direct_url("https://evilyoutu.be/x")
+    assert not mf._is_direct_url("https://youtube.com.evil.com/x")
+
+
+def test_is_direct_url_subdomains_true():
+    assert mf._is_direct_url("https://m.youtube.com/watch?v=abc")
+    assert mf._is_direct_url("https://on.soundcloud.com/x")
+    assert mf._is_direct_url("https://api.soundcloud.com/tracks/1")
+
+
 def _resolved(yt="https://music.youtube.com/watch?v=YYY"):
     return mf.Resolved(title="Bloom", artist="ODESZA",
                        thumb="https://img/cover.jpg", youtube_url=yt)