Migrate to ESLint 10 (flat config), @typescript-eslint v8, TypeScript 5.9, @types/node 22

[Copilot]

Upgrades the linting and TypeScript toolchain: ESLint 8→10, @typescript-eslint v6→v8, TypeScript 5.2→5.9, and aligns supporting packages. The repo already had a flat config (eslint.config.mjs), so no config format migration was needed.

package.json

• eslint: ^8.57.1 → ^10.0.0
• @eslint/js: added ^10.0.0 (now required as an explicit dep)
• @typescript-eslint/{eslint-plugin,parser}: ^6.21.0 → ^8.61.0
• eslint-config-prettier: ^8.3.0 → ^10.1.8
• eslint-plugin-import → replaced with eslint-plugin-import-x ^4.16.2 (maintained ESLint 10-compatible fork; all rules were already 'off' so this is a drop-in swap)
• typescript: ~5.2 → ~5.9

eslint.config.mjs

• Switch import to eslint-plugin-import-x
• Remove eslint-config-prettier from plugins (it's a config object, not an ESLint plugin)
• Remove rules deleted in @typescript-eslint v8: ban-types, no-loss-of-precision, no-extra-parens, no-var-requires
• no-empty-interface → no-empty-object-type (v8 rename); no-var-requires → no-require-imports (v8 rename)
• Suppress new rules added to @typescript-eslint v8 recommended to avoid flagging pre-existing code: no-unsafe-function-type, no-wrapper-object-types, no-unused-expressions
• Suppress new ESLint 10 core rules added to js.configs.recommended: no-unassigned-vars, no-useless-assignment, preserve-caught-error

Source files (11 files)

Removed stale // eslint-disable @typescript-eslint/ban-types directives from src/client/ and src/test/. The rule was removed in @typescript-eslint v8, causing ESLint to error on unresolvable rule references.

tsconfig.json / tsconfig.extension.json / pythonExtensionApi/tsconfig.json

Added "skipLibCheck": true to resolve a type conflict between @types/eslint-scope (transitive dep via webpack) and ESLint 10's newly bundled TypeScript declarations.

Original prompt

Migrate to ESLint 10 with flat config, types/node 22, and TypeScript 5.9.x. Create a PR.

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