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)).

agent/transports/codex_app_server_session.py

@@ -541,7 +541,7 @@ class CodexAppServerSession:
                 turn_status = (
                     (note.get("params") or {}).get("turn") or {}
                 ).get("status")
-                if turn_status and turn_status not in ("completed", "interrupted"):
+                if turn_status and turn_status not in {"completed", "interrupted"}:
                     err_obj = (
                         (note.get("params") or {}).get("turn") or {}
                     ).get("error")
@@ -775,9 +775,9 @@ def _approval_choice_to_codex_decision(choice: str) -> str:
     (verified against codex-rs/app-server-protocol/src/protocol/v2/item.rs
     on codex 0.130.0).
     """
-    if choice in ("once",):
+    if choice in {"once",}:
         return "accept"
-    if choice in ("session", "always"):
+    if choice in {"session", "always"}:
         return "acceptForSession"
     return "decline"