Redis-backed AccountProfile repository for velocity counters

[Teboho66]

Description

AccountProfile stores velocity counters (transactions per 1hr/6hr/24hr)
that must be updated atomically and queried in sub-millisecond time. This
issue replaces InMemoryAccountProfileRepository with a Redis-backed
implementation.

Tasks

• Install redis-py
• Create repositories/redis/redis_account_profile_repository.py
• Implement save() using Redis HSET
• Implement update_velocity() using Redis INCR (atomic — BR-AP2)
• Implement find_by_id() using Redis HGET
• Register REDIS as a new storage type in RepositoryFactory
• Write integration tests (requires Redis running via Docker)

Acceptance Criteria

• RepositoryFactory.get("AccountProfile", "REDIS") returns Redis impl
• Velocity counters increment atomically under concurrent load
• All existing A11 tests still pass with in-memory backend