indexio CLI missing --update flag: The MCP `indexio_build(update=True)` works bu

indexio CLI missing --update flag: The MCP indexio_build(update=True) works but the CLI indexio build doesn't expose --update. Add it so users can run indexio build --update --root /path from terminal to incrementally build only new/changed sources.

Related Notes

• issue-arash-20260328-193731-044867.md — Directly references this and other indexio/CLI bug reports filed today
• issue-arash-20260328-193442-340432.md — Related indexio build incremental mode feature — overlaps with --update flag functionality
• issue-arash-20260328-193406-431554.md — Another indexio CLI bug filed the same day
• issue-arash-20260328-192146-858687.md — Related indexio_build_status bug filed the same day — same subsystem
• issue-arash-20260326-174001-720656.md — MCP tools missing for index setup — related gap between MCP and CLI capabilities