chore(deps-dev): migrate ESLint to v9 with flat config

[Copilot]

Upgrades ESLint from v8 to v9 and migrates the config from .eslintrc.json (legacy format) to eslint.config.mjs (flat config). Replaces two deprecated packages and adds no extra compatibility shims.

Package changes

• eslint → ^9.39.4
• @typescript-eslint/{eslint-plugin,parser} → ^8.57.0; added typescript-eslint ^8.57.0
• eslint-plugin-sonarjs → ^4.0.2
• eslint-plugin-security → ^4.0.0
• eslint-plugin-jest → ^29.15.0
• eslint-plugin-no-secrets → ^2.3.3
• eslint-import-resolver-typescript → ^4.4.4
• eslint-plugin-array-func → ^5.1.1 (now ESM-only, flat config required)
• eslint-plugin-import → ^2.32.0
• eslint-plugin-node replaced with eslint-plugin-n ^17.24.0 (maintained fork; rules renamed n/*)
• eslint-plugin-eslint-comments replaced with @eslint-community/eslint-plugin-eslint-comments ^4.7.1
• eslint-plugin-deprecation removed — replaced by the built-in @typescript-eslint/no-deprecated rule (no extra package needed)
• Added globals ^15.15.0

Config migration

• eslint.config.mjs created; .eslintrc.json and .eslintignore removed
• deprecation/deprecation: warn replaced with @typescript-eslint/no-deprecated: warn — same behavior, no external plugin required
• Non-TypeScript files (.mjs, .cjs, .js) get tseslint.configs.disableTypeChecked to exclude them from typed linting
• New rules introduced by upgraded presets that have no equivalent in the previous config are explicitly turned off to preserve prior lint behavior: @typescript-eslint/only-throw-error, sonarjs/slow-regex, sonarjs/no-hardcoded-secrets, sonarjs/no-hardcoded-passwords, sonarjs/assertions-in-tests
• nullish-coalescing-operators added to n/no-unsupported-features/es-syntax ignores — eslint-plugin-n detects ?? usage against the Node 12.x engine range (old eslint-plugin-node missed this); the underlying compatibility issue requires separate author attention

Original prompt

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This section details on the original issue you should resolve

<issue_title>Update eslint to version 9</issue_title>
<issue_description>@copilot make the necessary changes to update eslint to version 9 and related dependencies, do this by going through the following PR:

• chore(deps-dev): bump @typescript-eslint/eslint-plugin from 5.62.0 to 8.34.1 #873
• chore(deps-dev): bump eslint from 8.57.0 to 9.38.0 #893
• chore(deps-dev): bump eslint-plugin-array-func from 3.1.8 to 5.1.1 #897
• chore(deps-dev): bump eslint-plugin-import from 2.31.0 to 2.32.0 #899
• chore(deps-dev): bump eslint-plugin-jest from 27.9.0 to 29.15.0 #900
• chore(deps-dev): bump eslint-plugin-no-secrets from 1.0.2 to 2.3.3 #902
• chore(deps-dev): bump eslint-import-resolver-typescript from 3.6.1 to 4.4.4 #904
• chore(deps-dev): bump eslint-plugin-security from 1.7.1 to 4.0.0 #905
• build(deps-dev): bump eslint-plugin-sonarjs from 0.25.0 to 4.0.2 #906

Instructions:

1. Create a new branch for all the changes
2. Do not bypass the current CI workflows
3. Only if necessary update other devDependencies
4. Important: do not add or remove any previous eslint rules
5. Fix any error caused by the new version of eslint
6. You can skip fixing warnings
7. When you finish open a PR and wait for review

References:

• https://eslint.org/docs/latest/use/migrate-to-9.0.0
• https://www.ekino.fr/publications/migrate-to-eslint-9-x/
• https://medium.com/@y.abdelkaderkharoubi/the-great-eslint-v9-migration-adventure-a-developers-survival-guide-%EF%B8%8F-ade6d75a11c5
• https://www.dhiwise.com/blog/design-converter/migration-to-eslint-v9-a-quick-and-simple-guide</issue_description>

<agent_instructions>Update only devDependencies and do not change the files inside .github or .devcontainer, but you can change the format of the source files if need it, other changes related to modification of complying with eslint rules must require the author intervention.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Update eslint to version 9 #907

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[leosuncin]

@copilot you can uninstall eslint-plugin-deprecation and replace it with @typescript-eslint/no-deprecated rule

[Copilot]

@copilot you can uninstall eslint-plugin-deprecation and replace it with @typescript-eslint/no-deprecated rule

Done in 95654ee. Removed eslint-plugin-deprecation and @eslint/compat, and replaced deprecation/deprecation: warn with @typescript-eslint/no-deprecated: warn in the flat config.

[leosuncin]

🎉 This PR is included in version 1.1.2 🎉

The release is available on GitHub release

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