chore: ruff auto-fix PLR6201 resweep — tuple → set in membership tests (#27355)

Six days after #23937 (608 fixes) the codebase had accumulated 241 new
PLR6201 violations. Same mechanical `x in (...)` → `x in {...}` fix,
same zero-risk profile: set lookup is O(1) vs O(n) for tuple and the
two are semantically equivalent for hashable scalar membership tests.

All 241 instances fixed via `ruff check --select PLR6201 --fix
--unsafe-fixes`, zero remaining. Every changed value is a hashable
scalar (str/int/None/enum/signal); no risk of unhashable runtime
errors. No behavior change.

Test plan:
- 119 files changed, +244/-244 (net zero) — exactly one-line edits
- `ruff check` clean afterward
- Compile checks pass on the largest touched files (cli.py, run_agent.py,
  gateway/run.py, gateway/platforms/discord.py, model_tools.py)
- Subset broad test run on tests/gateway/ tests/hermes_cli/ tests/agent/
  tests/tools/: 18187 passed, 59 pre-existing failures (verified against
  origin/main with the same shape — identical failure count, identical
  category — all xdist test-order flakes unrelated to this change)

Follows the same template as PR #23937 ([tracker: #23972](https://github.com/NousResearch/hermes-agent/issues/23972)).

plugins/google_meet/meet_bot.py

@@ -447,7 +447,7 @@ def _mac_audio_device_index(device_name: str) -> str:
 def run_bot() -> int:  # noqa: C901 — orchestration, explicit branches
     url = os.environ.get("HERMES_MEET_URL", "").strip()
     out_dir_env = os.environ.get("HERMES_MEET_OUT_DIR", "").strip()
-    headed = os.environ.get("HERMES_MEET_HEADED", "").lower() in ("1", "true", "yes")
+    headed = os.environ.get("HERMES_MEET_HEADED", "").lower() in {"1", "true", "yes"}
     auth_state = os.environ.get("HERMES_MEET_AUTH_STATE", "").strip()
     guest_name = os.environ.get("HERMES_MEET_GUEST_NAME", "Hermes Agent")
     duration_s = _parse_duration(os.environ.get("HERMES_MEET_DURATION", ""))
@@ -808,7 +808,7 @@ def _looks_like_human_speaker(speaker: str, bot_guest_name: str) -> bool:
     if not speaker or not speaker.strip():
         return False
     spk = speaker.strip().lower()
-    if spk in ("unknown", "you", bot_guest_name.strip().lower()):
+    if spk in {"unknown", "you", bot_guest_name.strip().lower()}:
         return False
     return True