## Motivation
Warnings that go unchecked tend to accumulate and hide real issues.
Treating them as errors ensures they are addressed immediately, both
locally during development and in CI.
## Changes
Added `SWIFT_TREAT_WARNINGS_AS_ERRORS = YES` and
`GCC_TREAT_WARNINGS_AS_ERRORS = YES` to the **project-level** Debug and
Release build configurations in `project.pbxproj`. This applies to all
targets (EXO, EXOTests, EXOUITests).
## Why It Works
Xcode's `SWIFT_TREAT_WARNINGS_AS_ERRORS` and
`GCC_TREAT_WARNINGS_AS_ERRORS` build settings promote Swift and C/ObjC
warnings to errors at compile time. Setting them at the project level
means all targets inherit the policy without needing per-target or
CI-level overrides.
## Test Plan
### Manual Testing
- Built the EXO scheme in Release configuration with `xcodebuild` — no
warning-as-error failures from Swift or C/ObjC sources.
### Automated Testing
- CI already builds with `-configuration Release`, so it will
automatically enforce warnings-as-errors via the inherited project
settings — no CI changes needed.
