[frontend] Add SEO metadata to all pages

[Ehonrie]

Use Next.js 14 Metadata API to add SEO and Open Graph tags to all pages.

Per page:

• Home: title 'BOXMEOUT - Boxing Prediction Market', description 'Bet on boxing matches with XLM on Stellar.'
• Market detail: dynamic title '{FighterA} vs {FighterB} | BOXMEOUT' with fight date in description
• Create: title 'Create Market | BOXMEOUT'
• Portfolio: title 'My Portfolio | BOXMEOUT'

All pages: og:title, og:description, og:type Open Graph tags.

Acceptance Criteria:

• Each page has a unique title and meta description
• Market detail has fighter names in the title
• Open Graph tags present on all pages
• Verified in browser DevTools

[Benedict315]

@Benedict315 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hello please assign me to this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Benedict315 to this issue.