Agent Skills: lisa-setup-notion

Configure Notion as the PRD source for this project. Walks the user through creating an internal integration in the target workspace, sharing the PRD database with it, stores the resulting `ntn_*` token in OS keychain (multi-workspace-safe — keyed by workspaceId), validates against the Notion API, and writes `notion.workspaceId`, `notion.prdDatabaseId`, and `notion.values` into `.lisa.config.json`. Idempotent — re-runs update the existing section rather than duplicating it. Offers to set top-level `source: \"notion\"`.