SearchIndex.query() fails on a client configured for RESP3 #825

Summary

Every SearchIndex.query() and AsyncSearchIndex.query() on a client created with protocol=3 raises AttributeError, for standalone and cluster clients alike. redis-py parses an FT.SEARCH reply into a dict on RESP3, and process_results reads .docs and .total from it as if it were a Result. clear(), and delete(drop=True) through it, fail the same way because they run a CountQuery.

Clients that RedisVL creates are unaffected, because RedisConnectionFactory sets protocol=2 unless the caller asks otherwise. A plain redis.Redis() or RedisCluster.from_url() with the default protocol is also unaffected, on redis-py 6.3 through 8.1. The failure needs a client passed in with protocol=3, or a URL with ?protocol=3.

Reproduction

Measured on main at 506b961b against Redis 8.4, with redis-py 6.3.0 and 8.1.0:

import redis
from redisvl.index import SearchIndex
from redisvl.query import CountQuery, FilterQuery
from redisvl.query.filter import FilterExpression, Tag

index = SearchIndex.from_dict(
    {"index": {"name": "r3", "prefix": "r3"}, "fields": [{"name": "t", "type": "tag"}]},
    redis_client=redis.Redis(protocol=3),
)
index.create(overwrite=True, drop=True)
index.load([{"t": "a"}])

index.query(FilterQuery(Tag("t") == "a"))
# AttributeError: 'dict' object has no attribute 'docs'   (index.py:544)

index.query(CountQuery(FilterExpression("*")))
# AttributeError: 'dict' object has no attribute 'total'  (index.py:483)

The async clients (redis.asyncio.Redis and redis.asyncio.cluster.RedisCluster) behave the same way with AsyncSearchIndex: they work on the default protocol and fail with the same two errors on protocol=3.

On a cluster client, create() and exists() also fail on RESP3 before any query runs, because of the raw FT.INFO reply; #795 fixes that part.

Cause

_parse_batch_search_result (redisvl/index/index.py:100) already handles this for pipelined searches: when _parse_results returns a dict, it converts it with redis-py's _parse_search_resp3 where that exists, and by hand on redis-py 6.x. The single-query path through _query and cluster_search hands the dict straight to process_results.

Acceptance

• query() returns the same results on a protocol=3 client as on protocol=2, for at least FilterQuery, VectorQuery and CountQuery, sync and async, standalone and cluster.
• clear() and delete(drop=True) work on a protocol=3 client.
• A regression test that fails before the fix. The cluster case needs a hermetic unit test, since cluster tests don't run on pull requests.