FEAT: Integrated Signal gateway and updated GTD

gtd.org

@@ -164,7 +164,16 @@ Slim down the org-agent microkernel by moving non-essential cognitive functions
     - Implemented `:telegram` actuator for outbound responses.
     - Refactored `org-skill-chat` to be channel-aware.
     - Verified with `gateway-telegram-tests.lisp`.
-**** TODO Implement org-skill-gateway-signal
+**** DONE Implement org-skill-gateway-signal
+    CLOSED: [2026-04-11 Sat 16:50]
+    :PROPERTIES:
+    :ID: gateway-signal-task
+    :END:
+    - Implemented `org-skill-gateway-signal.org` (signal-cli wrapper).
+    - Added background polling for `signal-cli receive --json`.
+    - Implemented `:signal` actuator for outbound responses.
+    - Updated `org-skill-chat` to support Signal channel.
+    - Verified with `gateway-signal-tests.lisp`.
 **** TODO Implement org-skill-gateway-matrix
 
 *** TRACK: DEPLOYMENT & INFRASTRUCTURE