fix(ui): replace Help with About in nav, refresh About page, microlearning spacing

[noor-lpi]

Navigation & footer

• Removed the Aide / Help tab from the top bar (instructions were obsolete). HelpComponent files are kept but no longer mounted, for a future rewrite.
• Moved À propos / About from the footer into that spot, with an "i" info icon.
• Removed Formulaire de retour / Feedback form from the footer (and its unused label + URL constant).

About page

• Removed the outdated video.
• Removed stray > characters from headings; body text is now left-aligned.
• Fixed heading hierarchy, logo alt text (partner names) and source links (_blanc → _blank + rel="noopener noreferrer").
• Copy pass in EN and FR: clearer About and partnership paragraphs, sentence-case headings in EN, consistent Oxford commas, French grammar fixes, non-breaking spaces before : ; and inside « », consistent "micro-learning" spelling.

Micro-learning

• Welcome screen now uses the full width on small screens and scales text down (previously a thin column).
• Side padding on the "Deux petites questions" / "Un dernier mot" steps.
• More spacing between the stacked header items on narrow screens, and between titles and subtitles (Bulma is-spaced).

Test plan

• Top bar shows About (info icon) instead of Help; footer shows only email + privacy policy
• About page in EN and FR, desktop and mobile widths
• Micro-learning welcome, auto-evaluation start/end and complete screens at mobile width

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