fix(a11y): resolve generic Action button ARIA labels across the application

[just-tanvi]

Description:

Overview

This PR fixes a widespread accessibility issue where the generic aria-label="Action button" attribute was override-masking visible button text, preventing screen readers from announcing correct actions. All buttons have been updated to adhere to WCAG 2.1 Success Criteria 4.1.2 (Name, Role, Value) and 1.1.1 (Non-text Content).

Details

• Number of files modified: 43 files (41 application files + 2 E2E test specifications).
• Number of aria-label="Action button" occurrences removed: 139+ occurrences.
• Button Refactoring Details:
  • Visible Text Buttons: Removed the aria-label="Action button" attribute entirely to allow standard text nodes (e.g. "Submit Project", "Save", "Cancel") to naturally serve as the accessible name.
  • Icon-Only Buttons: Replaced generic labels with meaningful descriptions:
    • Close modal / Close search
    • Search
    • Toggle theme
    • Delete item / Delete user / Delete event
    • Follow / Unfollow
    • Next step / Previous step
    • Open menu / Close menu

Test & Build Verification

• Next.js Production Build: Succeeded (npm run build).
• TypeScript Compilation: Passed (no type errors found).
• Unit Tests: Passed (17/17 Jest tests passed).
• E2E Tests: Passed (28/28 Playwright E2E tests passed after fixing strict-mode locator conflicts in login.spec.ts and roadmap.spec.ts).

closes #684