feat(api): implement Redis distributed lock manager

[Prajjwaltripathi20]

Summary

This PR adds a reusable Redis distributed lock manager for apps/api to provide safe concurrency control across processes.

Implementation

• Added LockService with atomic Redis SET NX PX lock acquisition.
• Uses crypto.randomUUID() to generate unique lock ownership tokens.
• Returns null when the lock is already held.
• Propagates Redis errors instead of treating them as successful lock acquisitions.
• Validates lock keys and TTL values.
• Added atomic Lua-based compare-and-delete logic for safe lock release.
• Prevents stale tokens from deleting locks owned by another process.
• Reuses the existing Redis client through CacheService.getRedisClient() without creating a new connection.
• Added the required pino logger configuration.

Testing

Added Vitest coverage for:

• Successful lock acquisition
• NX / PX parameters
• Lock contention
• Independent lock keys
• Token-matched release
• Stale/mismatched token rejection
• Redis acquisition and release errors
• Invalid keys
• Invalid TTL values
• Unavailable Redis client

Verification

• Vitest: 10/10 tests passing
• API TypeScript typecheck: 0 errors
• Monorepo TypeScript build: 0 errors
• Working tree: clean

Requirements Satisfied

• Atomic SET NX PX acquisition without preliminary GET
• Positive finite TTL validation
• crypto.randomUUID() ownership tokens
• Lock contention returns null
• Redis errors propagate correctly
• Atomic Lua compare-and-delete release
• Stale tokens cannot release another lock
• Existing Redis client reused
• No unnecessary Redis connections
• Comprehensive tests added