Migrate linting from ESLint + oxlint to single oxlint config

[Copilot]

Replaces the dual ESLint + oxlint setup with a single oxlint.config.ts. ESLint and all its associated packages are removed. Rules that oxlint can't cover natively are handled via oxlint's JS plugin support.

Strategy

• Categories over explicit rules: correctness: "error" and suspicious: "warn" replace ~100 individually listed rules.
• Native plugins: typescript and react (which includes react-hooks) cover TypeScript and React rule sets natively.
• JS plugins for gaps: Two plugins have no native oxlint equivalent and are loaded as JS plugins:
  • eslint-plugin-react-hooks (v7 absorbed the React Compiler rules from the now-removed eslint-plugin-react-compiler)
  • @tanstack/eslint-plugin-query

react-hooks alias requirement

react-hooks is a reserved name in oxlint (bundled into the native react plugin), so the JS plugin must be aliased:

jsPlugins: [
    { name: "react-hooks-js", specifier: "eslint-plugin-react-hooks" },
    "@tanstack/eslint-plugin-query",
],

Rules derived from plugin recommended configs

Instead of hardcoding individual rules, both JS plugins' recommended configs are spread dynamically. The rules block contains only overrides:

rules: {
    ...reactHooksRecommendedRules,   // from flat/recommended-latest, prefix remapped
    ...tanstackQueryRecommendedRules, // from flat/recommended
    "react/react-in-jsx-scope": "off",       // new JSX transform
    "react-hooks-js/exhaustive-deps": "off", // already covered natively as react/exhaustive-deps
},

Validation guards throw if either extraction produces an empty rule set, catching plugin API changes early.

Coverage gaps vs. original ESLint

Area	Status
Type-aware TypeScript rules (strictTypeChecked)	❌ oxlint doesn't support type-aware analysis; tsc still enforces type safety
react-refresh/only-export-components	❌ no oxlint equivalent
@typescript-eslint/no-deprecated	❌ type-aware

Levers for adjusting rule coverage

Goal	How
Fewer rules	Remove suspicious: "warn"; or turn off specific rules
More native rules	Add to plugins: "import", "promise", "unicorn", "jsx-a11y", "react-perf", "node"
React perf hints	Add "react-perf" to plugins + perf: "warn" to categories (expect many warnings on inline JSX)
More ESLint plugins	Add to jsPlugins — any ESLint v9-compatible plugin works
Stricter	Promote suspicious: "warn" → "error"

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