fix: normalize accountsChanged payload in FarcasterProvider

[amirosein-union]

Guard the host event boundary so malformed payloads (plain
string, object with .accounts, or other non-array) are coerced to
string[] before forwarding. Drops and warns on unrecognisable shapes to
prevent Wagmi's onAccountsChanged from calling .map() on a non-array.

[amirosein-union]

events were being forwarded raw to Wagmi's onAccountsChanged handler, which
unconditionally calls .map() on the payload. When the host emits a
non-array payload (plain string, object with an .accounts property, or
other malformed shape), this throws TypeError: accounts.map is not a
function, crashing the connector.

Root cause: FarcasterProvider blindly re-emitted all EIP-1193 events
with this.emit(event, ...args) without validating the accountsChanged
payload against the EIP-1193 spec (which requires string[]).

Fix: Added normalizeAccountsChangedPayload at the host event boundary
to coerce the three known malformed shapes into string[]. If the
payload is unrecognisable, the event is dropped with a console.warn
rather than forwarding a non-array and triggering the crash downstream.

[Juminstock]

Good direction overall. Two things that aren't coverable as inline comments:

Request path gap (line 77-79): handleWalletConnect casts the eth_requestAccounts response directly to Address[] and calls .map() on it. If Farcaster returns { accounts: [...] } from that method (the same non-standard shape this PR guards on the event side), .map() throws at runtime. Consider running that response through normalizeAccountsChangedPayload, or extracting a shared helper so both the event and request paths are protected.

Missing unit tests: normalizeAccountsChangedPayload is the core logic of this fix and has three branches, but no dedicated unit tests cover it. Each shape deserves its own test: plain string, valid string[], non-string array elements, { accounts: string[] }, { accounts: 'single-string' }, and an unrecognized shape. End-to-end forwarder tests won't catch element-type issues.

[Juminstock]

Array.isArray passes for any array regardless of element type, so a payload like [42, null] or [{ address: '0x...' }] clears this check and gets returned typed as string[]. Downstream callers that assume strings (.toLowerCase(), isAddress()) will throw at runtime with no warning.

Suggested fix:

if (Array.isArray(payload)) return payload.filter((v): v is string => typeof v === 'string')

Apply the same .filter to line 123 (the .accounts branch).

[Juminstock]

{ accounts: '0xabc' } (a single address as a string, not an array) falls through all three branches and returns undefined here, silently dropping the event. Array.isArray(payload) is false (it's an object), typeof payload === 'string' is false, and Array.isArray(payload.accounts) is false because '0xabc' is not an array.

Suggested fix, add this branch before return undefined:

if (typeof (payload as { accounts?: unknown }).accounts === 'string')
    return [(payload as { accounts: string }).accounts]