fix(links): update stale internal links and add missing redirects

[minimalsm]

Summary

• Updates footer links pointing to URLs that redirect (/eth/ -> /what-is-ether/, /enterprise/ -> external URL)
• Adds 5 permanent redirects for broken URLs that still receive external traffic

Added redirects

Broken URL	Redirect To	Referring Domains
/developers/docs/scaling/rollups	/developers/docs/scaling/	303
/eth2/get-involved/staking-community-grants	/staking/	159
/developers/docs/zk	/zero-knowledge-proofs/	69
/developers/docs/security	/developers/docs/smart-contracts/security/	65
/wallet	/wallets/	47

Test plan

• Footer links go directly to final destination (no redirect chain)
• New redirects resolve correctly (curl -IL)
• No redirect loops

[netlify]

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Lighthouse	7 paths audited Performance: 63 (🟢 up 8 from production) Accessibility: 94 (no change from production) Best Practices: 100 (no change from production) SEO: 100 (no change from production) PWA: 59 (no change from production) View the detailed breakdown and full score reports

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