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)).

tools/lazy_deps.py

@@ -450,7 +450,7 @@ def ensure(feature: str, *, prompt: bool = True) -> None:
             ).strip().lower()
         except (EOFError, KeyboardInterrupt):
             answer = "n"
-        if answer and answer not in ("y", "yes"):
+        if answer and answer not in {"y", "yes"}:
             raise FeatureUnavailable(
                 feature, missing, "user declined install at prompt"
             )

tools/mcp_tool.py

@@ -540,7 +540,7 @@ def _validate_remote_mcp_url(server_name: str, url: Any) -> str:
         raise InvalidMcpUrlError(
             f"Invalid MCP URL for '{server_name}': {stripped!r} ({exc})"
         ) from exc
-    if parsed.scheme.lower() not in ("http", "https"):
+    if parsed.scheme.lower() not in {"http", "https"}:
         raise InvalidMcpUrlError(
             f"Invalid MCP URL for '{server_name}': scheme must be http or "
             f"https, got {parsed.scheme!r} ({stripped!r})"

tools/video_generation_tool.py

@@ -286,9 +286,9 @@ def _coerce_bool(value: Any) -> Optional[bool]:
         return value
     if isinstance(value, str):
         v = value.strip().lower()
-        if v in ("true", "1", "yes", "on"):
+        if v in {"true", "1", "yes", "on"}:
             return True
-        if v in ("false", "0", "no", "off"):
+        if v in {"false", "0", "no", "off"}:
             return False
     return None
 

tools/x_search_tool.py

@@ -147,7 +147,7 @@ def _extract_response_text(payload: Dict[str, Any]) -> str:
             continue
         for content in item.get("content", []) or []:
             ctype = content.get("type")
-            if ctype in ("output_text", "text"):
+            if ctype in {"output_text", "text"}:
                 text = str(content.get("text") or "").strip()
                 if text:
                     parts.append(text)