test(playwright): initial playwright config and tests

[JosephKav]

Introduces Playwright for frontend e2e tests.

Test infrastructure

• playwright.config.ts - one project per browser (Chromium, Firefox, WebKit), each split into a parallel-safe project and a single-worker -mutating project for stateful flows (create/delete/ordering) that share one backend. Adds two mobile viewports (Pixel 8, iPhone 16) running the read-only/validation specs only.
• Makefile targets - playwright-tests-setup / -teardown / -tests / -full boot a managed Argus server (seeded from config.yml.example), poll its healthcheck, and tear it down cleanly.
• .github/workflows/playwright.yml - builds Argus (web + binary), starts the test server, type-checks, runs the suite across all browsers, uploads screenshots/traces/HTML report, and posts a results summary comment on PRs.

Coverage

• Dashboard & navigation.
• Service lifecycle - create -> verify -> refresh -> delete for GitHub, URL, manual, and URL (JSON / basic-auth / header-auth) lookups; update-available vs up-to-date status and the skip-release flow.
• Secret inheritance - masked header/basic-auth/webhook/notify secrets survive unrelated edits and service/notifier renames (verified end-to-end via real lookups, webhook sends, and Gotify test messages).
• Service ordering - drag-and-drop reorder + persistence in both grid and table views.
• WebHook actions - real send success/failure and the resend-blocked timer.
• Modal field validation - exhaustive per-field checks across Options, Command, ID/Name, Dashboard, Latest/Deployed Version (incl. url_commands, require, docker pairing), WebHook, and ~20 Notify types.

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Fixes & features (surfaced while building the e2e suite)

API / backend

• Serialise concurrent operations per service - a reference-counted per-service-ID lock: create/edit/delete take it exclusively, refreshes take it shared. Edit/delete wait out an in-flight op (so a background refresh can't bounce a user's save) then re-check the service still exists (it may have been renamed/deleted while waiting); create/refresh return 409 on conflict. OrderMu is released across the network verify so a slow CheckFetches can't block other services' order reads.
• Expose default latest_version/deployed_version type - /service/defaults now carries the default lookup type. The service-edit form builders drop their hardcoded UI fallback types (latest_version, deployed_version, require.docker, webhook) and inherit them from the defaults/hardDefaults response instead.
• Don't announce the initial manual version on create/edit - seeding a manual deployed_version during create/edit no longer broadcasts a VERSION/UPDATED event, so it no longer raises a spurious "Updated to version 'X'" toast; the version is still applied and persisted.
• Keep url lookup headers across edits - the censored config API now returns masked url-lookup headers and the edit-form schema carries headers for the url type, so the form no longer loads them empty and saving no longer drops them.
• Observe the WebSocket Hub clients off the Run loop - extract addClient/removeClient/broadcast and add a query channel so tests can observe the clients map without racing the Run goroutine's writes.

UI

• Keep an in-progress reorder when the server order changes - reconcile membership (drop removed ids, append new ones, keep the user's order) instead of resetting to the server order, so a concurrent create/delete elsewhere can't clobber a pending drag-reorder.
• Render FieldSet as a div to fix nested subgrid sizing - Chromium doesn't propagate subgrid track sizing through a <fieldset>, which the deeply-nested service-edit modal relies on; render as <div role="group">.
• Stable e2e hooks - data-update-available on the service card, an aria-label on the resend-timer hourglass, and IDs on field-check inputs.

Tooling / deps

• Migrate off deprecated Vite plugin options - native tsconfig path resolution, and vite-plugin-babel filter→include split into explicit .ts/.tsx passes.
• npm package bumps (fixes build(deps-npm-dev): update @types/node from 26.0.0 to 26.0.1 #899, build(deps-npm): update commitlint monorepo from 21.0.2 to 21.1.0 - autoclosed #898, build(deps): lock file maintenance #891, build(deps-npm-dev): update globals from 17.6.0 to 17.7.0 - autoclosed #857, build(deps-npm-dev): update @biomejs/biome from 2.5.0 to 2.5.1 - autoclosed #855, build(deps-npm): update vite from 8.1.0 to 8.1.2 #853, build(deps-npm): update @tanstack/react-query-devtools from 5.101.0 to 5.101.1 - autoclosed #844)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.70%. Comparing base (76363a3) to head (4fcf75c).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #900      +/-   ##
==========================================
+ Coverage   99.70%   99.70%   +0.01%     
==========================================
  Files         197      197              
  Lines       12451    12545      +94     
==========================================
+ Hits        12413    12507      +94     
  Misses         33       33              
  Partials        5        5              

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[github-actions]

✅ Playwright Test Results

	Count
✅ Passed	299
❌ Failed	0
🔄 Flaky	0
⏭️ Skipped	4

Duration: 942.2s

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