#523 - Replace DataManager dynamic usage with explicit dependencies

[brijesh-amin]

Parent: #523

Objective

Reduce hidden coupling and improve testability by moving from dynamic DataManager usage to explicit dependencies in targeted paths.

In scope

• Identify one or two high-traffic controllers/services using new DataManager(...)
• Replace with explicit repository/db dependency injection (module-level singleton or constructor-injected, based on repo conventions)
• Remove unused constructor argument patterns and tighten types where touched

Acceptance criteria

• No new new DataManager(config) call sites introduced
• Selected paths use explicit dependencies instead of dynamic proxy behavior
• Tests updated to mock explicit boundaries
• Behavior remains backward-compatible

Notes

Coordinate with the plan vertical-slice issue to avoid duplicate refactors.