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)).

gateway/platforms/discord.py

@@ -3639,18 +3639,18 @@ class DiscordAdapter(BasePlatformAdapter):
         configured = self.config.extra.get("thread_require_mention")
         if configured is not None:
             if isinstance(configured, str):
-                return configured.lower() not in ("false", "0", "no", "off")
+                return configured.lower() not in {"false", "0", "no", "off"}
             return bool(configured)
-        return os.getenv("DISCORD_THREAD_REQUIRE_MENTION", "false").lower() in ("true", "1", "yes", "on")
+        return os.getenv("DISCORD_THREAD_REQUIRE_MENTION", "false").lower() in {"true", "1", "yes", "on"}
 
     def _discord_history_backfill(self) -> bool:
         """Return whether history backfill is enabled for shared sessions."""
         configured = self.config.extra.get("history_backfill")
         if configured is not None:
             if isinstance(configured, str):
-                return configured.lower() not in ("false", "0", "no", "off")
+                return configured.lower() not in {"false", "0", "no", "off"}
             return bool(configured)
-        return os.getenv("DISCORD_HISTORY_BACKFILL", "true").lower() in ("true", "1", "yes")
+        return os.getenv("DISCORD_HISTORY_BACKFILL", "true").lower() in {"true", "1", "yes"}
 
     def _discord_history_backfill_limit(self) -> int:
         """Return the max number of messages to scan backwards for context.
@@ -3737,7 +3737,7 @@ class DiscordAdapter(BasePlatformAdapter):
                     break
 
                 # Skip system messages (pins, joins, thread renames, etc.)
-                if msg.type not in (discord.MessageType.default, discord.MessageType.reply):
+                if msg.type not in {discord.MessageType.default, discord.MessageType.reply}:
                     continue
 
                 # Respect DISCORD_ALLOW_BOTS for other bots.

gateway/run.py

@@ -8863,7 +8863,7 @@ class GatewayRunner:
                 lines.append("Failed/paused: (none)")
             return "\n".join(lines)
 
-        if action in ("pause", "resume"):
+        if action in {"pause", "resume"}:
             if not target:
                 return f"Usage: /platform {action} <name>"
             platform = _resolve_platform(target)