fix: add explicit hermes-api-server toolset for API server platform (#3304)

The API server adapter was creating agents without specifying
enabled_toolsets, causing ALL tools to load — including clarify,
send_message, and text_to_speech which don't work without interactive
callbacks or gateway dispatch.

Changes:
- toolsets.py: Add hermes-api-server toolset (core tools minus clarify,
  send_message, text_to_speech)
- api_server.py: Resolve toolsets from config.yaml platform_toolsets
  via _get_platform_tools() — same path as all other gateway platforms.
  Falls back to hermes-api-server default when no override configured.
- tools_config.py: Add api_server to PLATFORMS dict so users can
  customize via 'hermes tools' or platform_toolsets.api_server in
  config.yaml
- 12 tests covering toolset definition, config resolution, and
  user override

Reported by thatwolfieguy on Discord.

hermes_cli/tools_config.py

@@ -134,6 +134,7 @@ PLATFORMS = {
     "homeassistant": {"label": "🏠 Home Assistant", "default_toolset": "hermes-homeassistant"},
     "email":    {"label": "📧 Email",      "default_toolset": "hermes-email"},
     "dingtalk": {"label": "💬 DingTalk",   "default_toolset": "hermes-dingtalk"},
+    "api_server": {"label": "🌐 API Server", "default_toolset": "hermes-api-server"},
 }