Add Playwright E2E smoke tests (production-like build)

[kayodebristol]

Adds Playwright E2E smoke testing against built output (npm run build + preview).

Goal: catch "build green, UI broken" regressions by verifying at least one browser interaction.

Artifacts: Playwright traces/screenshots on failure.

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Note

Low Risk
Low risk: adds new E2E test tooling and a GitHub Actions workflow without changing runtime application code; main risk is CI flakiness or longer build times.

Overview
Adds Playwright-based E2E smoke coverage that runs against a production-like vite build + vite preview server, including a basic navigation/assertion and optional first-button click check.

Introduces a new GitHub Actions workflow to run E2E on PRs and main, installs Playwright browsers, and uploads the Playwright report artifact. Updates package.json/lockfile to include @playwright/test and adds test:e2e/test:all scripts, plus a playwright.config.ts webServer setup; flake.nix npm deps hash is updated accordingly.

^{Written by Cursor Bugbot for commit 750683c. This will update automatically on new commits. Configure here.}

[cursor]

Race condition in test after button click

Low Severity

The test captures innerText() immediately after btn.click() without waiting for async DOM updates. Since this app uses Svelte 5 (which batches state updates asynchronously), clicking a button likely triggers a reactive state change that updates the DOM in the next microtask. The synchronous expect(after).not.toEqual(before) assertion doesn't auto-wait, causing potential false negatives where the test fails despite the button working correctly. Playwright's auto-waiting assertions (like await expect(locator).not.toContainText(...)) are designed to handle this.

 

[kayodebristol]

CI Build was failing due to Nix fixed-output hash mismatch after package-lock change. I updated flake.nix to the new value from the CI log (got: sha256-bTjHsr/TVOZ850v+dxqcOre9hO+QopAIqgQNckiSf3M=). This should unblock the Nix Build job.

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cursor]

Missing npmDepsHash update breaks runebook-agent-pkg Nix build

High Severity

The npmDepsHash was updated for the frontend package but not for runebook-agent-pkg. Both packages use src = ./. and depend on the same package-lock.json, which changed when @playwright/test was added. The runebook-agent-pkg at line 123 still has the old hash (sha256-S2tAn2QEmj5ry9COmE/dxJEAjlxiugazvN9WxE/IyNE=), causing nix build .#runebook-agent to fail with a hash mismatch.