What this PR does

Before this PR:
The typescript/no-unnecessary-type-assertion rule was not enabled in oxlint, allowing redundant as X type assertions throughout the codebase.

After this PR:

• Enabled typescript/no-unnecessary-type-assertion as error in .oxlintrc.json
• Removed all unnecessary type assertions across 99 files (auto-fixed)

Why we need it and why it was done in this way

Unnecessary type assertions add noise and can mask real type issues. Enabling this lint rule keeps the codebase cleaner and ensures TypeScript's type inference is trusted where it's already correct.

The following tradeoffs were made: None

The following alternatives were considered: None

Breaking changes

None

Special notes for your reviewer

All changes were auto-fixed by the linter. The only manual change is the rule addition in .oxlintrc.json.

Checklist

• PR: The PR description is expressive enough and will help future contributors
• Code: Write code that humans can understand and Keep it simple
• Refactor: You have left the code cleaner than you found it (Boy Scout Rule)
• Upgrade: Impact of this change on upgrade flows was considered and addressed if required
• Documentation: A user-guide update was considered and is present (link) or not required. Check this only when the PR introduces or changes a user-facing feature or behavior.
• Self-review: I have reviewed my own code (e.g., via /gh-pr-review, gh pr diff, or GitHub UI) before requesting review from others

Release note

NONE