contrib: add telemetry event schema for wallet connect funnel

[Elizabethxxx]

Summary

Defines a consistent telemetry event schema for the wallet connect funnel (start to completion) and a withConnectTelemetry decorator that emits those events around WalletConnector.connectWallet.

closes #290

What's included

• A typed ConnectFunnelEvent union covering every step: connect_started, connect_webauthn_ceremony_started, connect_webauthn_ceremony_completed (carries the resolved keyId), connect_backend_lookup_started, connect_backend_lookup_completed (carries found), connect_session_key_rotated (schema slot for [medium] Rotate session key on passkeykit-connector re-authentication #223's rotation), and exactly one of connect_succeeded (accountId, durationMs) or connect_failed (failedAtStep, errorName, errorMessage, durationMs). Every event carries a shared connectionAttemptId so events from one call can be grouped, plus timestamp and network.
• No event carries secret or signature material — only public identifiers (keyId, accountId) and outcome metadata.
• withConnectTelemetry(connector, onEvent) wraps any WalletConnector (src/connector.ts) and emits the funnel through onEvent on every connectWallet() call. The hook is best-effort: a throwing handler is caught and never affects the underlying connect call. createWallet and signTransaction pass through unchanged.
• 8 tests: full event order on success, shared connectionAttemptId/network across one call's events, connect_succeeded payload correctness, keyId propagation, connect_failed payload and failedAtStep on a thrown error, telemetry-hook-throws-but-connect-still-resolves, no instrumentation leaking into createWallet/signTransaction, and distinct connectionAttemptIds across concurrent calls.

Placement note

The issue asks for "optional event emission hooks at each step in connector.ts". Contributor PRs may only touch contrib/, so this ships as a decorator around the existing WalletConnector interface rather than editing src/passkeykit-connector.ts directly. Because the decorator can only observe the WebAuthn ceremony and backend lookup as one opaque call from outside, it emits that started/completed pair around the single connectWallet call rather than at the true internal call sites. The README and code comments call this out explicitly: a maintainer merging this can lift the emission points directly into connectWallet in src/passkeykit-connector.ts (firing at the real ceremony/lookup/rotation call sites), which would be strictly more precise than the wrapper.

Test plan

• npx vitest run contrib/examples/issue-290-wallet-connect-telemetry — 8/8 passing
• Standalone strict typecheck of the new files passes with no errors

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