test: cover pause/unpause events and idempotent toggling

[Jagadeeshftw]

Summary

Adds test-only coverage (in contracts/escrow/src/test.rs) for the pause switch:

• pause() emits a paused event carrying the bool true; the contract reads paused.
• unpause() emits a paused event carrying the bool false; the contract reads unpaused.
• Double-pause and double-unpause are idempotent — is_paused stays consistent across repeated calls.
• A pause -> pause -> unpause sequence ends unpaused.

A module header note documents the covered behavior and records that auth is mocked (env.mock_all_auths()), so only the admin/happy path and idempotency are exercised; non-admin rejection is not asserted. No changes to lib.rs.

Closes #42

Test output

test result: ok. 28 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.20s

Security notes: Test-only change; admin-gating logic is unchanged and auth remains mocked in tests, so this adds no new trust assumptions.

[mikewheeleer]

solid coverage on the pause/unpause events and idempotency. merging 🚀