standardize public contract function signatures and access gates

[grantfox-oss]

public methods in lib.rs use mixed patterns for auth checks and error returns. Consolidate authorization and pause gating into shared helpers.

• Impacted files: app/contract/contracts/Folder/src/lib.rs, app/contract/contracts/Folder/src/admin.rs, app/contract/contracts/Folder/src/privacy.rs, app/contract/contracts/Folder/src/escrow.rs, app/contract/contracts/Folder/src/types.rs, app/contract/contracts/Folder/src/role_test.rs

[Neziahtech]

Hello Maintainer, I would love to solve this issue

[paud1615-tech]

Hello maintainers i who like for u to assign me this issue pls

[grantfox-oss]

🦊 GrantFox — @paud1615-tech has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #311)
2. Your PR will be reviewed by the BlockDash-Studios maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign | FWC26 campaign!

@paud1615-tech's PR #320 was approved and merged by @MaryammAli.

🏆 @paud1615-tech: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (226 total points). Track your full progress on GrantFox.

👏 Great work, @paud1615-tech! Keep contributing to BlockDash-Studios.