feat(skills): unified read-merge + authoring/override MCP tools

Adds the merged read surface (api/skill_catalog_view.py) over synced +
local stores with origin discrimination and override precedence, and
extends the skill MCP tools with create_skill/update_skill/delete_skill
that dispatch by origin (edit local skills; create/update/remove local
overrides for cloud skills). Wired into api.mcp.create_mcp_server.
Full non-integration suite green (564 passed).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

api/mcp.py

@@ -97,6 +97,7 @@ def create_mcp_server(
     manager: DeviceManager | None = None,
     skill_catalog_store: Any | None = None,
     skill_active_subscriptions: set[str] | None = None,
+    skill_local_store: Any | None = None,
 ) -> Any:
     try:
         from mcp.server.fastmcp import FastMCP
@@ -166,10 +167,13 @@ def create_mcp_server(
 
     if skill_catalog_store is not None:
         from api.skill_catalog_mcp import register_skill_catalog_tools
+        from storage.local_skills import LocalSkillStore
 
+        local_store = skill_local_store or LocalSkillStore()
         register_skill_catalog_tools(
             server,
             store=skill_catalog_store,
+            local_store=local_store,
             get_active_subscriptions=lambda: set(skill_active_subscriptions or set()),
             get_registered_tools=lambda: set(handlers.keys()),
         )