[CI/CD] Redis service container in GitHub Actions for middleware integration tests

[nanaf6203-bit]

Problem Statement

.github/workflows/ci.yml runs middleware tests but lacks a Redis service container. Tests targeting distributed rate limiter (#16) fail or fall through to mocks.

Acceptance Criteria

• A redis:7-alpine service in the CI workflow
• Tests connect at redis://localhost:6379
• Healthcheck step ensures Redis ready before tests start

Implementation Notes

services:
  redis:
    image: redis:7-alpine
    options: --health-cmd "redis-cli ping" --health-interval 10s

Files Likely Affected

• .github/workflows/ci.yml

Difficulty / Effort

• Difficulty: Easy
• Effort: T-Shirt S

Labels

ci-cd, priority:medium, area:infrastructure