deprecate catalogue-matching functions

[SaInekK]

Per your comment on #132:

we are not using the catalogue instruments method any more because it got replaced with a Weaviate index (https://harmonydata.ac.uk/search) as it did not scale, so I need to mark the match_questions_with_catalogue_instruments method as deprecated and remove it

This PR does step 1 — adds a DeprecationWarning and a .. deprecated:: docstring note to the three public catalogue entry points in src/harmony/matching/matcher.py:

• match_instruments_with_catalogue_instruments
• match_questions_with_catalogue_instruments
• match_query_with_catalogue_instruments

The warning message points users to https://harmonydata.ac.uk/search. No behaviour change — existing callers continue to work.

A small test file (tests/test_catalogue_deprecation_warnings.py) pins that each entry point emits a DeprecationWarning whose message mentions Weaviate, so the deprecation cannot silently disappear later.

Removal of the functions themselves is left for a follow-up PR (next major version).