[Typescript Conversion: Level 18]: Convert app/scripts/controllers/permissions/specifications.js to typescript

## **Description**

Convert `app/scripts/controllers/permissions/specifications.js` from JavaScript to TypeScript as part of the TS migration initiative.

## **Scenario (for user stories only)**

_(Not applicable)_

## **Design (for user stories only)**

_(Not applicable)_

## **Technical Details (for technical tasks only)**

- Convert this file to TypeScript.
- Migration Level: **18**
- Dependencies:
- shared/constants/permissions.ts
- Dependents:
- app/scripts/controllers/permissions/index.js
- app/scripts/controllers/permissions/specifications.test.js

## **[Threat Modeling Framework](https://github.com/adamshostack/4QuestionFrame) (for technical tasks only)**

- What are we working on? Convert file to TypeScript.
- What can go wrong? Type errors, integration mismatches, missing types.
- What are we going to do about it? Write types carefully and test thoroughly.
- Did we do a good job? _(To be evaluated)_

## **Acceptance Criteria**

- File is fully converted to TypeScript.
- Tests pass.
- File adheres to linting rules.
- Functionality remains unchanged.

## **Stakeholder Review (for MetaMask employees only)**

- [X] Engineering
- [ ] Design
- [ ] Product
- [ ] QA
- [ ] Security
- [ ] Legal
- [ ] Marketing
- [ ] Management
- [ ] Other

## **References**

- Parent issue: #31460

Start with app/scripts/controllers/permissions/specifications.js and the dependency shared/constants/permissions.ts, then inspect app/scripts/controllers/permissions/index.js and specifications.test.js for expected exports and behavior. Convert the file without changing functionality, run the permissions specifications tests, and verify linting passes.

Written by the indexing model from the issue text.