chore: update all examples and dependencies to Widget V4 beta

[chybisov]

Which Linear task is linked to this PR?

EMB-333

Why was it implemented this way?

Bulk dependency upgrade + full v3→v4 migration of all 22 examples to align with the Widget V4 beta architecture.

Key changes:

• All dependencies upgraded to latest via pnpm up -r -L
• TypeScript 5.9 → 6.0 with deprecated options removed (esModuleInterop, moduleResolution: "Node", allowSyntheticDefaultImports)
• 15 examples migrated from v3 stable to v4 beta @lifi/* packages
• Added @lifi/widget-provider-ethereum and SDK-based useChains hook to wallet-connected examples
• Moved useSyncWagmiConfig/convertExtendedChain/isExtendedChain imports from wallet-management → widget-provider-ethereum
• wagmi v2 → v3 upgrade across affected examples
• Fixed Privy SDK v3 breaking changes, ChainType.STL exclusion, @solana/web3.js type conflicts
• Next.js ^14/^15/^16 versions preserved per example
• workspace:* references kept unchanged

All 22 examples and all core packages build successfully.

Visual showcase (Screenshots or Videos)

N/A — no visual changes, dependency and import updates only.

Checklist before requesting a review

• I have performed a self-review and testing of my code.
• This pull request is focused and addresses a single problem.
• If this PR modifies the Widget API or adds new features that require documentation, I have updated the documentation in the public-docs repository.