feat(valkey): shared cache config + ValkeyCache for A2A and file uploads

Extract duplicated Redis URL parsing into a shared cache_config utility.
Introduce ValkeyCache as a lightweight async key/value cache using
valkey-glide. Wire it into A2A task handling, agent card caching, and
file upload caching.

Part 1/4 of Valkey storage implementation.

fix: async-safe embeddings and resilient drain_writes

Add bytes→float validators on MemoryRecord and ItemState to handle
Valkey returning embeddings as raw bytes. Make embed_texts() safe when
called from an async context by using a thread pool. Improve
drain_writes() with per-save timeouts and error logging instead of
raising on failure.

Part 3/4 of Valkey storage implementation.

feat(valkey): ValkeyStorage vector memory backend

Add ValkeyStorage, a distributed StorageBackend implementation using
Valkey-GLIDE with Valkey Search for vector similarity. Wire it into
Memory as the 'valkey' storage option. Pin scrapegraph-py<2 to fix
unrelated upstream breakage.

Part 4/4 of Valkey storage implementation.

fix: use datetime.utcnow() for last_accessed consistency

MemoryRecord defaults use utcnow() for created_at and last_accessed.
Match that in ValkeyStorage.update_record() to avoid timezone
inconsistency in recency scoring.

feat(valkey): shared cache config + ValkeyCache for A2A and file uploads

Extract duplicated Redis URL parsing into a shared cache_config utility.
Introduce ValkeyCache as a lightweight async key/value cache using
valkey-glide. Wire it into A2A task handling, agent card caching, and
file upload caching.

Part 1/4 of Valkey storage implementation.

fix: handle non-numeric database path in cache URL parsing

Extract _parse_db_from_path() helper that catches ValueError for
paths like /mydb and defaults to 0 with a warning, instead of
crashing.

fix: async-safe embeddings and resilient drain_writes

Add bytes→float validators on MemoryRecord and ItemState to handle
Valkey returning embeddings as raw bytes. Make embed_texts() safe when
called from an async context by using a thread pool. Improve
drain_writes() with per-save timeouts and error logging instead of
raising on failure.

Part 3/4 of Valkey storage implementation.

fix: catch concurrent.futures.TimeoutError for Python 3.10 compat

In Python <3.11, concurrent.futures.TimeoutError is distinct from the
builtin TimeoutError. Catch both so the timeout warning path works
on all supported Python versions.

pyproject.toml

@@ -205,6 +205,8 @@ override-dependencies = [
     "gitpython>=3.1.50,<4",
     "langsmith>=0.7.31,<0.8",
     "authlib>=1.6.11",
+    # scrapegraph-py 2.x removed Client class; pin until upstream fixes type ignores
+    "scrapegraph-py>=1.46.0,<2",
 ]
 
 [tool.uv.workspace]