feat: Add GET /contests endpoint with pagination, filtering, and Redis caching

[simplicityf]

Description:

This PR implements the GET /contests endpoint with the following features:
- Pagination using page and limit query parameters
- Filtering by contest type and status
- 30-second Redis caching to reduce database load on repeated queries
This improves performance and allows more flexible querying of contest data.

Also wrote a test case:
GET /api/contests
- returns contests with default pagination (19 ms)
- returns cached results when available (1 ms)
- filters by sport (1 ms)
- filters by fee range (2 ms)
- handles pagination correctly (1 ms)
- returns 400 for invalid query parameters
- continues without cache on Redis errors
- returns 500 on database errors (1 ms)
- combines multiple filters correctly (1 ms)
(Note: All unit test passed)

Related issue: closes #10

[simplicityf]

@PoulavBhowmick03 please review

[PoulavBhowmick03]

@simplicityf please fix the build errors

[simplicityf]

@PoulavBhowmick03, I have resolve it. The test is not coming from my side

Or did i break a code 🤔