feat(grok): give the Grok Secretary its CEO-authority tools (blocker)

The Grok Secretary could chat but had zero directive tools — it could not read
company state or act on a CEO command, so it was non-functional. This is the
integration blocker.

- secretary-tools.js: opencode plugin registering read_company_state /
  read_task / submit_directive via the Hooks.tool API, each calling
  /api/secretary/* with the container's HMAC agent token — a direct port of the
  Claude Secretary's SDK tools (secretary_driver.build_secretary_options). The
  high-impact directive kinds stay gated server-side (queued for CEO confirm).
- agent-grok-secretary.Dockerfile: bake the plugin and scope it to this image
  via ROBOCO_OPENCODE_EXTRA_PLUGINS, so only the Secretary carries CEO authority.
- grok_secretary_main: correct the docstring that falsely claimed the tools
  reached the API "through the mounted MCP gateway" (there is no gateway mount;
  they're an opencode plugin).
- secretary.md: name the three tools and restate the confirm-before-act gate.

Verified locally that opencode loads a file-path plugin importing
@opencode-ai/plugin and resolves the package; the live model-tool-call +
backend round-trip is flagged UNVERIFIED-LIVE for the NAS.

docker/agent-grok-secretary.Dockerfile

@@ -3,13 +3,22 @@
 # The Grok analogue of agent-secretary. Holds a PERSISTENT `opencode serve`
 # session open, receives the CEO's messages over HTTP (POST /turn on :9000), and
 # streams each reply back to the panel via the relay. The Secretary's CEO-
-# authority tools (read_company_state / read_task / submit_directive) reach the
-# API through the mounted MCP gateway + the HMAC agent token. Builds on the Grok
+# authority tools (read_company_state / read_task / submit_directive) are
+# registered as opencode tools by the secretary-tools.js plugin, which calls
+# /api/secretary/* with the container's HMAC agent token. Builds on the Grok
 # runtime image; the driver renders opencode.json from the spawn env first.
 # =============================================================================
 
 FROM roboco-agent-grok
 
+USER root
+
+# The CEO-authority tool plugin (read_company_state / read_task / submit_directive).
+# Scoped to THIS image via ROBOCO_OPENCODE_EXTRA_PLUGINS so only the Secretary
+# carries CEO authority; opencode_config appends it to the plugin array.
+COPY docker/grok/secretary-tools.js /app/opencode-plugins/secretary-tools.js
+ENV ROBOCO_OPENCODE_EXTRA_PLUGINS=/app/opencode-plugins/secretary-tools.js
+
 USER agent
 
 LABEL role="grok-secretary"