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/cron/test_cron_no_agent.py

@@ -68,7 +68,7 @@ def test_create_job_no_agent_stores_field(hermes_env):
     assert job["no_agent"] is True
     assert job["script"] == "watchdog.sh"
     # Prompt can be empty/None for no_agent jobs.
-    assert job["prompt"] in (None, "")
+    assert job["prompt"] in {None, ""}
 
 
 def test_create_job_default_is_not_no_agent(hermes_env):
@@ -148,7 +148,7 @@ def test_cronjob_tool_update_toggles_no_agent(hermes_env):
 
     off = json.loads(cronjob(action="update", job_id=job_id, no_agent=False, prompt="run"))
     assert off["success"] is True
-    assert off["job"].get("no_agent") in (False, None)
+    assert off["job"].get("no_agent") in {False, None}
 
     on = json.loads(cronjob(action="update", job_id=job_id, no_agent=True))
     assert on["success"] is True