🔧 Migrate and Refactor `PageHeader` Component to Vue 3

[tholulomo]

📋 Description

This subtask is part of the Nanomine Pages and Components Migration to Vue 3 Epic. The goal is to refactor and migrate the existing PageHeader component from its current implementation to align with Vue 3 best practices.

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✅ Tasks

1. Migrate to Vue 3

• Refactor the current PageHeader component from a class-based component to the Vue 3 Composition API.
• Convert the existing JavaScript implementation to TypeScript for improved type safety and maintainability.

2. Style Refactoring

• Migrate and update any component-specific SCSS styling.
• Ensure styles are modular and scoped correctly to the PageHeader.

3. Unit Testing

• Add or update unit tests for the refactored PageHeader component.
• Ensure proper test coverage for expected props, computed values, and render output.

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🧪 Acceptance Criteria

• PageHeader is implemented using Vue 3 + Composition API.
• Component is written in TypeScript.
• Styles are properly migrated and scoped.
• Unit tests are present and passing.
• No breaking changes introduced to existing header usage.

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🔀 Branch

Commit changes to a feature branch named:
feature/vue3-page-header-migration

🔗 Related Epic

This task is a subtask of: 📦 Nanomine Pages and Components Migration to Vue 3