Fix ESLint flat config format in yennefer-observatory

[Copilot]

The ESLint configuration was using the legacy extends property, which is invalid in flat config format (ESLint v9+).

Changes:

• Removed extends property from configuration object
• Placed plugin configurations (js.configs.recommended, reactHooks.configs.flat.recommended, reactRefresh.configs.vite) directly in the top-level config array

Before:

export default defineConfig([
  globalIgnores(['dist']),
  {
    files: ['**/*.{js,jsx}'],
    extends: [
      js.configs.recommended,
      reactHooks.configs.flat.recommended,
      reactRefresh.configs.vite,
    ],
    // ...
  },
])

After:

export default defineConfig([
  globalIgnores(['dist']),
  js.configs.recommended,
  reactHooks.configs.flat.recommended,
  reactRefresh.configs.vite,
  {
    files: ['**/*.{js,jsx}'],
    // ...
  },
])

This enables proper config composition and plugin rule activation in ESLint's flat config system.

---

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[Igor Holt (igor-holt)]

Fix

[Copilot]

Pull request overview

Update yennefer-observatory to use ESLint v9+ flat config composition by removing legacy extends usage and composing plugin configs at the top level.

Changes:

• Removed extends from the per-files config object
• Added js, react-hooks, and react-refresh recommended configs directly to the top-level config array

Files not reviewed (1)

• yennefer-observatory/package-lock.json: Language not supported

[Copilot]

This changes the scope of the recommended configs: previously they were applied only to **/*.{js,jsx} via the object that contained files, but now these configs apply globally (to every file ESLint considers). To keep the prior behavior, wrap/clone each recommended config entry with the same files glob (e.g., by spreading the config object and adding files) or move them into the same scoped config block so they only affect JS/JSX.

Suggested change

	js.configs.recommended,
	reactHooks.configs.flat.recommended,
	reactRefresh.configs.vite,
	{
	files: ['**/*.{js,jsx}'],
	{
	files: ['**/*.{js,jsx}'],
	...js.configs.recommended,
	},
	{
	files: ['**/*.{js,jsx}'],
	...reactHooks.configs.flat.recommended,
	},
	{
	files: ['**/*.{js,jsx}'],
	...reactRefresh.configs.vite,
	},
	{
	files: ['**/*.{js,jsx}'],