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>
