Clear POI overlay markers when all categories are unchecked

[vshcherb]

Fixes #1945 — after the POI Overlay is disabled in Configure Map, the orange POI icons stayed on the map until a manual page refresh.

Cause

PoiLayer's main effect started with:

if ((!isEmpty(ctx.showPoiCategories) && zoom !== prevZoom) || move || isTypeChange) { ... }
else if (isEmpty(ctx.showPoiCategories)) { /* clearPoiList() lives here */ }

move is the moveend timestamp from useZoomMoveMapHandlers and is never reset, so it stays truthy after the first map move (which happens on load). The first branch therefore always won; inside it if (ctx.showPoiCategories.length > 0) was false, so nothing happened — and the branch that calls clearPoiList() when the category list becomes empty was never reached.

Fix

Check the empty-categories case first, then the zoom/move/type-change refresh. The nested ctx.showPoiCategories.length > 0 check is now redundant and is dropped.

Test

New selenium test search/100-poi-overlay-disable.mjs: enables the Cafe and restaurant category, checks the markers appear, unchecks it, and waits for them to disappear. It fails on main (waitByRemoved times out on se-poi-marker-background-#f8931d-circle) and passes with the fix.

Verified locally against localhost:3000 (dev server proxied to test.osmand.net): search (11), map (2) and menu (6) suites all pass.

AI disclaimer

Produced with Claude Code (Opus 5).

Prompts used (summarised):

1. Reproduce and fix issue POI Overlay icons remain visible on the map after the overlay is disabled #1945, using the local web dev server (no postgres) and the local maps folder.
2. Create the pull request, and add a web UI test for this — it is a bad enough problem to be worth covering.

Decided by the agent, not requested explicitly:

• Root-cause choice of fix: reordering the branches in PoiLayer's effect (checking the empty-category case first) rather than resetting the move flag after each refresh; the redundant nested length > 0 check was dropped as part of it.
• Placement, name and shape of the regression test (tests/selenium/src/tests/search/100-poi-overlay-disable.mjs), modelled on the existing 91-poi-markers-test.mjs.
• Running the neighbouring search, map and menu suites as a regression check, and confirming the new test fails on the unfixed code before claiming it covers the bug.