feat(tool): register optional discord_control tool in whispergate plugin and align defaults

plugin/README.md

@@ -27,4 +27,20 @@ Optional:
 - `enabled` (default true)
 - `discordOnly` (default true)
 - `bypassUserIds` (default [])
-- `endSymbols` (default punctuation set)
+- `endSymbols` (default ["🔚"])
+- `enableDiscordControlTool` (default true)
+- `discordControlApiBaseUrl` (default `http://127.0.0.1:8790`)
+- `discordControlApiToken`
+- `discordControlCallerId`
+
+## Optional tool: `discord_control`
+
+This plugin now registers an optional tool named `discord_control`.
+To use it, add tool allowlist entry for either:
+- tool name: `discord_control`
+- plugin id: `whispergate`
+
+Supported actions:
+- `channel-private-create`
+- `channel-private-update`
+- `member-list`