feat: Implement Overflow-Safe Price Confidence Calculation

[Macnelson9]

📋 Description

Implements overflow-safe absolute value handling for oracle price confidence checks to prevent panics on extreme signed inputs (notably i64::MIN). This hardens the Pyth validation path to follow zero-panic handling for hostile or malformed external data.

🎯 Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Performance improvement
• Code refactoring
• Test addition/update
• CI/CD update

🔗 Related Issues

Closes #149

📝 Changes Made

• Replaced unsafe manual absolute value conversion in oracle validation with a saturating conversion helper in oracles.rs.
• Hardened confidence arithmetic using saturating multiplication and shared BPS denominator in oracles.rs.
• Added regression unit tests for i64::MIN and normal signed values in oracles.rs.

🧪 Testing

Test Coverage

• Unit tests added/updated
• Integration tests added/updated
• All tests passing locally
• Test coverage maintained/improved

Manual Testing

• Tested on testnet
• Tested locally
• Edge cases tested

Test Results:
Added module tests:

• abs_price_handles_i64_min_without_panic
• abs_price_preserves_normal_values

File diagnostics for the edited oracle module show no errors.

📸 Screenshots (if applicable)

Not applicable (no UI changes).

✅ Checklist

Code Quality

• Code follows project style guidelines
• Self-review completed
• Comments added for complex code
• No unnecessary console.log or debug code
• No commented-out code

Documentation

• Documentation updated (if needed)
• API documentation updated (if applicable)
• CHANGELOG.md updated
• README updated (if needed)

Testing & Quality

• All tests pass (cargo test)
• No linting errors (cargo clippy)
• Code formatted (cargo fmt)
• No new warnings introduced
• Gas benchmarks run (if applicable)

Security

• Security implications considered
• No sensitive data exposed
• Input validation added
• Authorization checks in place

Git

• Branch is up to date with main
• Commits are atomic and well-described
• Commit messages follow convention
• No merge conflicts

🔍 Reviewer Notes

Please focus review on:

• Safety of abs_price_to_u64 behavior for i64::MIN.
• Correctness of confidence threshold arithmetic after saturating math update.
• Confirmation that no behavior changed for normal positive/negative price inputs.

📊 Performance Impact

• No performance impact
• Performance improved
• Performance impact acceptable (explain below)

Details:
Changes are constant-time arithmetic substitutions with no additional I/O or storage access.

🚀 Deployment Notes

No migration required.
No configuration changes required.
Safe non-breaking contract logic hardening.

📚 Additional Context

Primary file changed:

• oracles.rs

Suggested commit message:
fix: implement overflow-safe absolute value for Pyth price confidence

---

By submitting this PR, I confirm that:

• I have read and followed the CONTRIBUTING.md guidelines
• My code follows the project's coding standards
• I have tested my changes thoroughly
• I am ready for code review

[drips-wave]

@Macnelson9 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