Upgrade eslint-config-expensify to 4.0.6

[roryabraham]

Summary

• Upgrades eslint-config-expensify from 2.0.108 to 4.0.6 and replaces the monolithic import expensify from 'eslint-config-expensify' config with modular sub-configs (browser, react, typescript, jest, scripts), matching the pattern used in expensify-common.
• Removes the hand-rolled @typescript-eslint plugin/parser block and ~40 per-rule overrides that duplicated what v4 now ships (type imports/exports, import extensions, redeclare handling, JSDoc disables, etc.).
• Adds eslint-seatbelt with an initial baseline (eslint.seatbelt.tsv) to grandfather existing type-checked violations from the jump to recommendedTypeChecked, without blocking CI.
• Removes unused direct ESLint plugin dependencies (eslint-plugin-import, eslint-plugin-jsx-a11y, eslint-plugin-react, @typescript-eslint/*, @lwc/eslint-plugin-lwc, @react-native-community/eslint-config) now provided transitively by eslint-config-expensify.
• Removes stale eslint-disable comments for rules that v4 no longer reports (dot-notation, @typescript-eslint/no-empty-function).

Overrides retained (by category)

Onyx / project-structure specific (intentional):

Override	Scope	Why
rulesdir/no-multiple-onyx-in-file: off	all source	This repo is Onyx; tests and mocks intentionally create multiple instances
import/extensions: off	tests/**, mocks	Test utilities import without extensions
no-restricted-syntax (allow for...of / for...in)	tests	Tests use iteration patterns blocked by the default airbnb syntax rule
@typescript-eslint/no-require-imports: off	**/*.native.ts(x)	React Native platform files use require()
globals.jest	MemoryOnlyProvider.ts	Test-only provider accessed from Jest mocks
globalIgnores for .github/**, dist/**, cpp/**, etc.	n/a	Bundled GH Action output, build artifacts, and local bench/C++ dirs are not lint targets

Not Onyx-specific (generic library / TypeScript conventions — candidates to remove over time):

Override	Why it exists
class-methods-use-this: off	Same relaxation App uses for TS/React codebases
es/no-optional-chaining: off	Expensify-wide relaxation (Hermes / toolchain compatibility)
es/no-nullish-coalescing-operators: off	Expensify-wide relaxation
react/prop-types: off	TypeScript project; prop-types are redundant
react/require-default-props: off	TypeScript project; default props enforced via types
react/jsx-props-no-spreading: off	Library hook/components (useOnyx) spread props intentionally

Deliberately not imported:

• eslint-config-expensify/expensify — contains App-only rulesdir/* rules (prefer-onyx-connect-in-libs, no-onyx-connect, restricted react-native imports, etc.) that do not apply to this package.

Test plan

CI only.

Linked E/App PR

Expensify/App#95893

Author Checklist

• I linked the correct issue in the ### Related Issues section above
• I linked the corresponding Expensify/App PR in the ### Linked E/App PR section above, and verified this change against it (E/App CI passed and manual testing completed)
• I wrote clear testing steps that cover the changes made in this PR
  • I added steps for local testing in the Tests section
  • I tested this PR with a High Traffic account against the staging or production API to ensure there are no regressions (e.g. long loading states that impact usability).
• I included screenshots or videos for tests on all platforms
• I ran the tests on all platforms & verified they passed on:
  • Android / native
  • Android / Chrome
  • iOS / native
  • iOS / Safari
  • MacOS / Chrome / Safari
• I verified there are no console errors (if there's a console error not related to the PR, report it or open an issue for it to be fixed)
• I followed proper code patterns (see Reviewing the code)
  • I verified that any callback methods that were added or modified are named for what the method does and never what callback they handle (i.e. toggleReport and not onIconClick)
  • I verified that the left part of a conditional rendering a React component is a boolean and NOT a string, e.g. myBool && <MyComponent />.
  • I verified that comments were added to code that is not self explanatory
  • I verified that any new or modified comments were clear, correct English, and explained "why" the code was doing something instead of only explaining "what" the code was doing.
  • I verified proper file naming conventions were followed for any new files or renamed files. All non-platform specific files are named after what they export and are not named "index.js". All platform-specific files are named for the platform the code supports as outlined in the README.
  • I verified the JSDocs style guidelines (in STYLE.md) were followed
• If a new code pattern is added I verified it was agreed to be used by multiple Expensify engineers
• I followed the guidelines as stated in the Review Guidelines
• I tested other components that can be impacted by my changes (i.e. if the PR modifies a shared library or component like Avatar, I verified the components using Avatar are working as expected)
• I verified all code is DRY (the PR doesn't include any logic written more than once, with the exception of tests)
• I verified any variables that can be defined as constants (ie. in CONST.js or at the top of the file that uses the constant) are defined as such
• I verified that if a function's arguments changed that all usages have also been updated correctly
• If a new component is created I verified that:
  • A similar component doesn't exist in the codebase
  • All props are defined accurately and each prop has a /** comment above it */
  • The file is named correctly
  • The component has a clear name that is non-ambiguous and the purpose of the component can be inferred from the name alone
  • The only data being stored in the state is data necessary for rendering and nothing else
  • If we are not using the full Onyx data that we loaded, I've added the proper selector in order to ensure the component only re-renders when the data it is using changes
  • For Class Components, any internal methods passed to components event handlers are bound to this properly so there are no scoping issues (i.e. for onClick={this.submit} the method this.submit should be bound to this in the constructor)
  • Any internal methods bound to this are necessary to be bound (i.e. avoid this.submit = this.submit.bind(this); if this.submit is never passed to a component event handler like onClick)
  • All JSX used for rendering exists in the render method
  • The component has the minimum amount of code necessary for its purpose, and it is broken down into smaller components in order to separate concerns and functions
• If any new file was added I verified that:
  • The file has a description of what it does and/or why is needed at the top of the file if the code is not self explanatory
• If the PR modifies a generic component, I tested and verified that those changes do not break usages of that component in the rest of the App (i.e. if a shared library or component like Avatar is modified, I verified that Avatar is working as expected in all cases)
• If the main branch was merged into this PR after a review, I tested again and verified the outcome was still expected according to the Test steps.
• I have checked off every checkbox in the PR author checklist, including those that don't apply to this PR.