feat(plugins): add main window plugins hub

docs/features/cua-plugin-icon/spec.md

@@ -0,0 +1,49 @@
+# CUA Plugin Icon
+
+## User Need
+
+The CUA Computer Use official plugin should be easier to recognize in the plugin hub and detail page.
+
+## Goal
+
+Use `lucide:laptop-minimal-check` for `com.deepchat.plugins.cua` instead of the generic puzzle icon.
+
+## Acceptance Criteria
+
+- The added plugins row shows the CUA plugin with `lucide:laptop-minimal-check`.
+- The plugin catalog card shows the CUA plugin with `lucide:laptop-minimal-check`.
+- The CUA plugin detail header shows `lucide:laptop-minimal-check`.
+- Other non-special official plugins keep the generic puzzle icon.
+
+## UI Sketch
+
+Before:
+
+```text
++---------------------------+
+| [puzzle] CUA Computer Use |
++---------------------------+
+```
+
+After:
+
+```text
++-----------------------------------------+
+| [laptop-minimal-check] CUA Computer Use |
++-----------------------------------------+
+```
+
+## Constraints
+
+- Keep the change renderer-only.
+- Do not add a manifest icon field for a single plugin.
+- Do not change plugin runtime behavior.
+
+## Non-Goals
+
+- Redesign plugin cards.
+- Add configurable icon infrastructure.
+
+## Open Questions
+
+- None.