docs: rewrite wallet section around WalletAdapter

[GazzyLee]

Summary

Updates apps/docs/architecture/frontend.md to reflect the wallet abstraction layer introduced in the "feat(web): extract wallet abstraction layer from Freighter flow" commit.

The doc previously claimed connection goes through connectFreighter(), which no longer exists. Callers now depend on the WalletAdapter interface (apps/web/src/lib/wallet.ts), implemented today only by FreighterWallet.

Motivation

• connectFreighter() is confirmed absent from apps/web/src. useWalletConnect now calls wallet.connect() on a FreighterWallet.
• The abstraction layer is the exact seam the queued multi-wallet issues (xBull, LOBSTR) plug into, so it belongs in the architecture doc.

Changes

• Rewrote the Wallet store section to describe the real flow:
  • useWalletConnect calls wallet.isInstalled() → wallet.connect(), then persists the public key.
  • The store revalidates a restored key via wallet.isAuthorized().
• Briefly documents the WalletAdapter interface and how a new wallet is added (new WalletAdapter implementation + selection in wallet.ts, no caller changes).
• Removed the only remaining connectFreighter() reference.

Acceptance Criteria

• frontend.md wallet section reflects wallet.connect() via WalletAdapter, not connectFreighter()
• Documents the WalletAdapter interface and how a new wallet gets added
• No remaining doc references to connectFreighter()

Scope

Field	Value
Area	Docs
Protocol affected	None
Network	both
Breaking change?	No

Closes #521

[vercel]

@GazzyLee is attempting to deploy a commit to the Collins' projects Team on Vercel.

A member of the Team first needs to authorize it.

[collinsezedike]

The PR title is cut off mid-word (...drop connectFreighte…), and the commit message header is 82 characters, over the 72-character limit enforced by the commit message ruleset. Since squash merge is enforced, the PR title becomes the final commit message (see CONTRIBUTING.md's Commit Convention section), so please fix the title itself, not just the commit, and keep it at or under 72 characters.

[collinsezedike]

@GazzyLee the PR title is still truncated. This hasn't been updated since the earlier review. Please fix the title itself, since it becomes the squash commit message on merge.

[collinsezedike]

I have fixed the title myself.


@GazzyLee Thank you for your contribution. Your PR matches the WalletAdapter flow accurately.


Feel free to pick up another open issue if you're interested.

Merging now.