Admin webhook commands added; MCP tools renamed

Minor Changes

• 5d191ea: Add releases admin webhook commands for managing outbound webhook subscriptions: add, list, show, edit, remove, test, rotate-secret, and deliveries. These wrap the existing root-key-gated /v1/webhooks API routes so Phase-A operators can manage subscriptions without raw API calls.

  The subscriber-facing webhook verify (local signature check, no auth) moves from admin webhook verify to top-level webhook verify.

• 313ffb0: Rename the local stdio MCP server's tools (releases admin mcp serve) to mirror the canonical names served by the hosted server at mcp.releases.sh: search_releases → search (now returns the full unified result — orgs, catalog, and releases — with an optional type section filter), list_sources + list_products → list_catalog (org-scoped via GET /v1/orgs/:slug/catalog; global path folds products + standalone sources), and get_product → get_catalog_entry (dispatches product vs. source on the identifier prefix). get_source / get_source_changelog are unchanged.