Flip @typescript-eslint/no-unused-vars from "warn" to "error" in
oxlint.json (with argsIgnorePattern/varsIgnorePattern of "^_" and
caughtErrors "none"), and clean up the resulting violations across the
frontend.
Fixes favor proper cleanup over underscore hacks: genuinely dead
imports, variables, and destructured props are removed; parameters are
only "_"-prefixed when their position is required by an external or
callback signature (event handlers, render props, antd validators,
forwardRef, or omit-from-rest destructuring).
Note: the .eslintrc.js half of the prior attempt (#37886) is obsolete
since the frontend migrated to oxlint as the primary linter.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>