fix(song-ref): don't misparse NetEase collection URLs / trailing-punct ids (#90 follow-up)

Corner-case review of the #90 play-by-id parser found two reachable issues:

- A NetEase playlist/album/artist/toplist/djradio share URL (which reuses ?id=)
  was matched as a SONG id, so pasting one into !play called getSongDetail() on
  a collection id and returned a confusing 'No song found' instead of falling
  back to a normal search. Guard the id= branch to exclude collection pages.
- The id: prefix captured trailing punctuation from a chat paste ('id:12345.' ->
  '12345.'), which then failed to resolve. Strip trailing .,;)] from the id.

Both fall back to safe behavior (plain search / clean id). Tests added for
collection URLs and pasted ids with punctuation.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/bot/song-ref.test.ts

@@ -15,6 +15,23 @@ describe("parseSongRef (#90 exact-song selection)", () => {
     expect(parseSongRef("ID: 004Z8Ihr0JIu5s")).toEqual({ id: "004Z8Ihr0JIu5s", platform: null });
   });
 
+  it("strips trailing punctuation from a pasted id:", () => {
+    expect(parseSongRef("id:185868.")).toEqual({ id: "185868", platform: null });
+    expect(parseSongRef("id:185868)")).toEqual({ id: "185868", platform: null });
+    expect(parseSongRef("id:185868,")).toEqual({ id: "185868", platform: null });
+  });
+
+  it("does NOT treat NetEase collection (playlist/album/artist) URLs as a song id", () => {
+    // These reuse ?id= but are not songs — they should fall through to search,
+    // not misresolve to getSongDetail(collectionId) and error "no song".
+    expect(parseSongRef("https://music.163.com/playlist?id=123456")).toBeNull();
+    expect(parseSongRef("https://music.163.com/#/playlist?id=123456")).toBeNull();
+    expect(parseSongRef("https://music.163.com/album?id=123456")).toBeNull();
+    expect(parseSongRef("https://music.163.com/artist?id=185858")).toBeNull();
+    // A genuine song URL is still parsed.
+    expect(parseSongRef("https://music.163.com/song?id=185868")).toEqual({ id: "185868", platform: "netease" });
+  });
+
   it("parses NetEase song URLs", () => {
     expect(parseSongRef("https://music.163.com/song?id=185868")).toEqual({ id: "185868", platform: "netease" });
     expect(parseSongRef("https://music.163.com/#/song?id=185868&userid=1")).toEqual({ id: "185868", platform: "netease" });