[OUSD-16] Miscellaneous General Comments

[sparrowDom]

Fixes here:

• IWETH9 Interface Used For Non-WETH Assets
• Missing Documentation For _nextYield() Function
• Confusing Variable Name oUSD Used For Multiple Token Types

[codecov]

Codecov Report

❌ Patch coverage is 92.30769% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 33.15%. Comparing base (327a6eb) to head (0f1e698).

Files with missing lines	Patch %	Lines
contracts/contracts/vault/VaultCore.sol	91.66%	1 Missing ⚠️

Additional details and impacted files

@@                    Coverage Diff                    @@
##           clement/simplify-ousd    #2788      +/-   ##
=========================================================
- Coverage                  34.34%   33.15%   -1.20%     
=========================================================
  Files                        124      124              
  Lines                       5488     5453      -35     
  Branches                    1450     1441       -9     
=========================================================
- Hits                        1885     1808      -77     
- Misses                      3602     3644      +42     
  Partials                       1        1              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.