WCAG add pagination to title

[BarbaraOliveira13]

🎩 What?

This PR addresses the issue where the current page number and the total number of pages were missing from the <title> tag on paginated proposal index pages.

🎩 Why?

This change aligns with WCAG 2.4.2 - Page Titled
and WCAG 2.4.8 - Location. It provides users with clear and contextual information about their location within paginated content.

📌 Related Issues

decidim#13809

WCAG 2.4.2 - Page Titled
WCAG 2.4.8 - Location

Steps to Test

1. Navigate to a paginated proposals index page in your local environment (e.g., /processes/budget-participatif/f/1/proposals?page=2).
2. Inspect the <title> tag in the browser’s developer tools.
3. Confirm the title includes:

• The current page number
• The total number of pages

📋 Subtasks

• Updated the <title> tag in decidim-proposals/app/views/decidim/proposals/proposals/index.html.erb to dynamically include: the current page number and the total number of pages in the paginated proposals list.
• If there's a new public field, add it to GraphQL API
• Add documentation regarding the feature
• Add/modify seeds
• Add tests
• Another subtask

📷 Screenshots (optional)

Additional context
This issue originates from an accessibility audit funded by the city of Lyon, targeting compliance with RGAA and corresponding WCAG standards. The changes ensure clearer navigation and improved usability for assistive technologies.

[github-actions]

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[Quentinchampenois]

Hello,
The title content should be in a translation key