feat(tools): fabric-send-message + fabric-channel-list + fabric-message-history

Plugin previously had no way for an agent to send text into a specific
channel proactively — outbound went only through the channel-reply
path (responds to the channel that woke the agent). discussion-complete
internally called client.postMessage but only for the close-time
summary, no general-purpose surface.

Three new tools (+ declare existing fabric-canvas / fabric-channel that
were registered but missing from contracts.tools so agents couldn't
see them per the openclaw plugin contract):

  * fabric-send-message {guildNodeId, channelId, content}
      → {ok, messageId, seq}
    Author = calling agent. Use for ARD broadcasts, follow-ups in a
    different channel, etc.

  * fabric-channel-list {guildNodeId, nameFilter?, xType?, includeClosed?}
      → {ok, count, channels[]}
    Backend filters to public + member channels; nameFilter is client-
    side case-insensitive substring; xType / includeClosed apply post-
    fetch. Returns id/name/xType/lastSeq so callers can pipe into the
    other tools.

  * fabric-message-history {guildNodeId, channelId, seqFrom?, seqTo?, limit?}
      → {ok, page, messages[]}
    Tail-by-default: omit seqFrom/seqTo and the tool fetches the
    channel head from listChannels then asks for [head-limit+1, head].
    Limit default 20, max 200. Backend rejects non-participants.

Plus 3 supporting client methods (listChannels, listMessages — both
GET via existing req helper).

contracts.tools updated to declare these 5 (3 new + 2 previously-
silent ones). Verified earlier in sim restart logs: openclaw warned
'plugin tool is undeclared (fabric): fabric-canvas / fabric-channel'
so agents couldn't use them despite registerTool firing.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

openclaw.plugin.json

@@ -14,7 +14,12 @@
       "create-work-channel",
       "create-report-channel",
       "create-discussion-channel",
-      "discussion-complete"
+      "discussion-complete",
+      "fabric-canvas",
+      "fabric-channel",
+      "fabric-send-message",
+      "fabric-channel-list",
+      "fabric-message-history"
     ]
   },
   "configSchema": {