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)).

tests/honcho_plugin/test_session.py

@@ -1570,7 +1570,7 @@ class TestDialecticLifecycleSmoke:
         self._await_thread(provider)
         assert mgr.dialectic_query.call_count == 2, "turn 4 cadence fire"
         _, kwargs = mgr.dialectic_query.call_args
-        assert kwargs.get("reasoning_level") in ("medium", "high"), \
+        assert kwargs.get("reasoning_level") in {"medium", "high"}, \
             f"long query must bump reasoning level above 'low'; got {kwargs.get('reasoning_level')}"
         assert provider._last_dialectic_turn == 4, "cadence tracker advances on success"