Add Trip Editor asset-mode smoke checks

[stef-k]

Summary

Implements #297 Batch 6 only: explicit opt-in Trip Editor asset-mode smokes.

• Adds tools/trip-editor-asset-smoke.mjs.
• Adds opt-in npm scripts:
  • npm run smoke:trip-editor:assets:dev
  • npm run smoke:trip-editor:assets:published
  • npm run smoke:trip-editor:assets
• Documents asset-mode boundaries in docs/22-Testing.md.
• Adds committed .gitignore coverage for smoke output directories.
• Fixes a Development asset-mode bug where the Trip Editor shell could emit stale production CSS from an existing Vite manifest.

Asset Claims

The Development smoke verifies ASP.NET Development + Vite dev-server asset wiring.

The published smoke builds and publishes the app, launches that published output on an allocated local URL by default, and verifies production assets are served without Vite dev-server requests.

These smokes prove asset loading and published-output serving only. They do not prove Trip Editor CRUD persistence or editor workflow behavior; those are covered by the dedicated #297 CRUD, error-state, search-add, and rich-notes contract batches.

Published Smoke Guardrails

• Uses an allocated 127.0.0.1 port by default.
• Rejects a configured WAYFARER_ASSET_SMOKE_PUBLISHED_URL if it already responds before launch.
• Ties readiness to the spawned published process staying alive.
• Reports log/stdout/stderr tails if the child exits early.

Validation

• npm run smoke:trip-editor:assets:published: passed.
• npm run smoke:trip-editor:assets:dev: passed.
• npx playwright test --config=playwright.config.ts --list: passed, 117 tests listed.
• dotnet build: passed.
• dotnet test: passed, 1547 tests.
• LOC check: passed with existing warning-threshold files only.
• git diff --check origin/main...HEAD: passed.
• tracked/untracked artifact scan: clean.

Full Trip Editor E2E remains intentionally deferred for the final #297 validation pass after this batch merges.