feat(x_search): gated X (Twitter) search tool with OAuth-or-API-key auth (#26763)

* feat(x_search): gated X (Twitter) search tool with OAuth-or-API-key auth

Salvages tools/x_search_tool.py from the closed PR #10786 (originally by
@Jaaneek) and reworks its credential resolution so the tool registers
when EITHER xAI credential path is available:

* XAI_API_KEY (paid xAI API key) is set in ~/.hermes/.env or the env, OR
* The user is signed in via xAI Grok OAuth — SuperGrok subscription —
  i.e. hermes auth add xai-oauth has been run

Both paths route through xAI's built-in x_search Responses tool at
https://api.x.ai/v1/responses. When both credentials exist OAuth wins,
matching tools/xai_http.py's existing preference order (uses SuperGrok
quota instead of paid API spend).

The check_fn calls resolve_xai_http_credentials() which auto-refreshes
the OAuth access token if it's within the refresh skew window, so a
True return means the bearer is fetchable AND non-empty.

Wiring
- tools/x_search_tool.py — new tool, ~370 LOC. Schema gated by check_fn,
  bearer resolved per-call so revoked OAuth surfaces a clean tool_error
  rather than an HTTP 401.
- toolsets.py — "x_search" toolset def. NOT added to _HERMES_CORE_TOOLS;
  users opt in via hermes tools.
- hermes_cli/tools_config.py — CONFIGURABLE_TOOLSETS entry + TOOL_CATEGORIES
  block with two provider options (OAuth + API key) sharing the existing
  xai_grok post_setup hook for credential bootstrap.
- hermes_cli/config.py — DEFAULT_CONFIG["x_search"] with model /
  timeout_seconds / retries. Additive nested key; no version bump.
- tests/tools/test_x_search_tool.py — 13 tests covering HTTP shape,
  handle validation, citation extraction, 4xx/5xx/timeout handling,
  and the full credential-resolution matrix (OAuth-only, API-key-only,
  both-set, neither-set, resolver-raises, config overrides, registry
  registration).
- website/docs/guides/xai-grok-oauth.md — adds X Search to the
  direct-to-xAI tools section with off-by-default note.
- website/docs/user-guide/features/tools.md — new row in the tools table.

Off by default — users enable via `hermes tools` → 🐦 X (Twitter) Search.
Schema only appears to the model when xAI credentials are configured.

Co-authored-by: Jaaneek <Jaaneek@users.noreply.github.com>

* docs(x_search): add dedicated feature page + reference entries

- website/docs/user-guide/features/x-search.md (new) — full feature
  walkthrough: authentication, enablement, configuration, parameters,
  returned fields, example, troubleshooting, see-also links.
- website/docs/reference/tools-reference.md — new "x_search" toolset
  section with parameter docs and credential gating note.
- website/docs/reference/toolsets-reference.md — new row in the
  toolset catalog table.
- website/sidebars.ts — wires the new feature page under
  Media & Web, after web-search.

---------

Co-authored-by: Jaaneek <Jaaneek@users.noreply.github.com>

hermes_cli/config.py

@@ -1603,6 +1603,23 @@ DEFAULT_CONFIG = {
         "servers": {},
     },
 
+    # X (Twitter) Search via xAI's built-in x_search Responses tool.
+    # The tool registers when xAI credentials are available (SuperGrok
+    # OAuth or XAI_API_KEY) AND the x_search toolset is enabled in
+    # `hermes tools`. These settings tune the backing Responses API call.
+    "x_search": {
+        # xAI model used for the Responses call. grok-4.20-reasoning is
+        # the recommended default; any Grok model with x_search tool
+        # access works.
+        "model": "grok-4.20-reasoning",
+        # Request timeout in seconds (minimum 30). x_search can take
+        # 60-120s for complex queries — the default is generous.
+        "timeout_seconds": 180,
+        # Number of automatic retries on 5xx / ReadTimeout / ConnectionError.
+        # Each retry backs off (1.5x attempt seconds, capped at 5s).
+        "retries": 2,
+    },
+
     # Config schema version - bump this when adding new required fields
     "_config_version": 23,
 }