chore(deps): bump @honeybbq/teamspeak-client to 0.2.1, drop ts6-compat shim

Version 0.2.1 ships a universal clientinit format that works natively
against both TS3 and TS6 servers:

    client_version: "3.?.? [Build: 5680278000]"
    client_version_sign: DX5NIYLvfJEUjuIbCidnoeozxIDRRkpq3I9vVMBmE9L2qnekOo
                         BzSenkzsg2lC9CMv8K5hkEzhr2TYUYSwUXCg==

The old ts6-compat.ts workaround (monkey-patching handler.sendPacket to
rewrite clientinit's client_version to "3.6.2") is now actively wrong:
it replaces the library's new correct version/signature pair with a
stale one that TS6 servers reject, which is why the first 0.2.1 TS6
handshake attempt still hung at `received initivexpand2`.

Changes:
- package.json: "@honeybbq/teamspeak-client": "^0.1.0" -> "^0.2.1"
- src/ts-protocol/client.ts: remove patchClientInitVersion import and
  the sendPacket monkey-patch block. Leave an inline comment so anyone
  reading the git blame understands why the shim is gone.
- Delete src/ts-protocol/ts6-compat.ts and ts6-compat.test.ts — no
  callers remain.

Other 0.2.x notes worth knowing (no code change here, just documenting):
- ClientOptions gained serverPassword / defaultChannel /
  defaultChannelPassword that are sent DURING clientinit. We still call
  our own joinChannel() post-connect because the existing flow works
  and switching is an orthogonal refactor.
- 0.1.1 contains the P-256 DER encoding fix (PR #5 by ZHANGTIANYAO1).
  Identities generated by 0.1.0 are cryptographically incompatible with
  0.2.x's corrected handshake path — a bot whose identity column was
  populated before this upgrade will hang at `received initivexpand2`
  and fall through the 15s connect deadline. Workaround: clear the
  identity column so the next start generates a fresh key. Server
  groups assigned to the old UID must be re-granted once against the
  new one.

Verification:
- tsc --noEmit clean
- vitest: 93/93 unit tests pass (1 test file removed with ts6-compat)
- scripts/test_full_feature.py against a local TS6 server: 51/51 pass,
  including handshake, voice playback, identity persistence, WebSocket
  stateChange broadcasts, and all corner-case regressions.
- Live: bot connected to TS6 in ~80ms after identity regeneration,
  played NetEase audio through the voice channel, clean stop.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

package.json

@@ -15,7 +15,7 @@
   "license": "MIT",
   "dependencies": {
     "@discordjs/opus": "^0.10.0",
-    "@honeybbq/teamspeak-client": "^0.1.0",
+    "@honeybbq/teamspeak-client": "^0.2.1",
     "@koa/router": "^15.4.0",
     "@sansenjian/qq-music-api": "^2.2.9",
     "axios": "^1.14.0",