Add Trip Editor search-add persistence coverage

[stef-k]

Summary

Implements #297 Batch 4 only: focused Playwright coverage for Trip Editor map search Add as place persistence after #295.

The tests mock only the geocode provider/search response. Save Place is not mocked: it posts to the real create-place endpoint, verifies success feedback and visible sidebar placement, rereads the editor API, reloads the page, and verifies persistence again.

Covered:

• Unassigned Places default target and persistence.
• One selected normal-region add and persistence.
• Fresh search-add target reset back to Unassigned Places.
• Pending marker and Add Place draft defaults (marker + bg-blue).

Out Of Scope

• Batch 5 rich-notes sanitizer/persistence.
• Batch 6 published production asset smoke.
• Product behavior changes.

Validation

• Focused spec: 2 passed.
• npx playwright test --config=playwright.config.ts --list: passed, 116 tests listed.
• dotnet build: passed.
• dotnet test: passed, 1537 tests.
• LOC check: passed under hard cap; warnings are existing large files, not the new 263-line spec.
• git diff --check origin/main...HEAD: passed.
• tracked artifact scan: clean.