test: add missing coverage for treasury pause guard and plans controller

[valoryyaa-byte]

Summary

• Adds a Rust test asserting the treasury contract's pause guard blocks both deposit and withdraw while paused, and that normal operation resumes after unpausing. Also adds the missing pause check to withdraw itself, which previously had no pause guard despite the test expectations.
• Adds a unit spec for PlansController covering request parsing (route/query params, body dto, authenticated user id) and delegation to PlansService for create, list, findOne, update, and remove.

Closes #2048
Closes #2047

[drips-wave]

@valoryyaa-byte Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits