feat: add catalog discovery CLI commands (#2360)

* feat: add catalog discovery CLI commands

* fix: address second Copilot review

* fix: address third Copilot review

* fix: align catalog remove with displayed order

* fix: route local catalog config errors to local guidance

* fix: address integration catalog review feedback

* fix: accept numeric string catalog priorities

* fix: align catalog remove with visible entries

* fix: preserve invalid catalog root validation

* fix: include invalid catalog priority value

* fix: preserve falsy catalog root validation

* fix: clarify integration catalog guidance

* fix: align integration catalog list and remove

* fix: align integration catalog edge cases

* fix: clarify catalog error guidance tests

* fix: clarify integration catalog edge cases

* fix: harden integration catalog removal

* fix: validate integration state before catalog search

* fix: reject empty integration catalog URL

* fix: allow catalog remove to clean non-string URLs

* fix: address catalog env and priority review

* fix: align catalog source display names

* fix: align catalog fallback names