feat: add E2E testing package with Playwright

[N-45div]

Summary

Adds a Playwright E2E testing package for wallet connection testing, addressing #77.

Changes

• New package: @solana/e2e at tests/e2e/
• Wallet harness abstraction: Resilient interface for Phantom, Solflare, Backpack
• Happy path tests: Wallet connection/disconnection flows
• CI workflow: .github/workflows/e2e.yml for automated E2E testing
• Turbo integration: Added test:e2e task

Test Results

• 2 tests pass (basic UI verification)
• 4 tests skip gracefully (require wallet extensions)

How to Test Locally

pnpm install
pnpm --filter @solana/e2e exec playwright install chromium
pnpm --filter @solana/e2e test

Closes #77

[GuiBibeau]

@N-45div Am i understanding that running the test in headed mode is needed to work with extension wallets? If that's the case i think we need to review a bit the approach i proposed in #77. The goal here was to have a higher level of confidence than the unit tests.

Let's either research a way to add a wallet-standard injected script or get the full test suite running here against extension in CI.

What do you think?

[N-45div]

Thanks for the feedback @GuiBibeau ! I've updated the PR with a mock wallet-standard implementation.

Changes

• Added tests/e2e/src/mock-wallet/ with a wallet-standard compliant mock wallet
• The mock wallet is injected via Playwright's addInitScript before page load
• Tests now run without real browser extensions in CI

Test Results

• 7 passed (5 mock wallet tests + 2 basic UI tests)
• 6 skipped (extension-dependent tests)

How it works

The mock wallet implements the wallet-standard interface (standard:connect, standard:disconnect, standard:events, solana:signMessage, solana:signTransaction) and registers itself with the wallet-standard registry. This allows the framework-kit app to discover and connect to it just like a real wallet extension.

This approach provides higher confidence than unit tests while being reliable in CI without needing actual browser extensions.

Let me know if you'd like any changes!