fix(pagination): clamp page to prevent u32 overflow

[Emelie-Dev]

Description

Fixes an issue where providing extremely large values for the page query parameter (such as u32::MAX) caused a silent wraparound overflow in release builds and a panic in debug builds when computing the pagination offset.

This PR prevents this behavior by checking for u32 arithmetic overflow, returning a clean validation error if the parsed page results in an uncomputable offset, and explicitly enforces integer overflow checks system-wide in release builds.

Changes

• Checked Pagination Math: Updated the offset computation in TransactionService::list_for_user to use checked_sub and checked_mul. This explicitly yields an AppError::Validation if an overflow occurs, resulting in a predictable 422 Unprocessable Entity response.
• Test Coverage: Added compute_offset unit tests in src/services/transaction.rs covering typical inputs, extremely high values near the u32 boundary, and out-of-bounds page parameters to verify proper error propagation.
• Release Overflow Protection: Enabled overflow-checks = true in the [profile.release] section of Cargo.toml. This acts as defense in depth against this class of bug appearing anywhere else in the application logic.

Validation and Testing

• Offset logic behaves predictably at upper boundaries (tested page = 1, page = 42949673, and page = u32::MAX).
• The application will now return a Validation error properly when passing bounds, terminating execution safely.
• Code passes local cargo fmt and cargo check.

Related Issues

• Resolves: TransactionListParams.page/per_page unchecked u32 multiplication overflow issue

closes #57

[abayomicornelius]

resolve conflicts

[Emelie-Dev]

@abayomicornelius