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/cli.py

@@ -159,7 +159,7 @@ def _cmd_setup() -> int:
     print("---------------------")
 
     system = _p.system()
-    system_ok = system in ("Linux", "Darwin")
+    system_ok = system in {"Linux", "Darwin"}
     print(f"  platform       : {system}  [{'ok' if system_ok else 'unsupported'}]")
 
     try:
@@ -231,7 +231,7 @@ def _cmd_install(*, realtime: bool, assume_yes: bool) -> int:
     import subprocess as _sp
 
     system = _p.system()
-    if system not in ("Linux", "Darwin"):
+    if system not in {"Linux", "Darwin"}:
         print(f"google_meet install: {system} is not supported (linux/macos only)")
         return 1
 
@@ -242,7 +242,7 @@ def _cmd_install(*, realtime: bool, assume_yes: bool) -> int:
             ans = input(f"{prompt} [y/N] ").strip().lower()
         except EOFError:
             return False
-        return ans in ("y", "yes")
+        return ans in {"y", "yes"}
 
     print("google_meet install")
     print("-------------------")