Add cell type filter to heightmap editor brush panel

[Copilot]

Description

Adds a cellTypeFilter select input to the heightmap editor brush panel, allowing users to restrict brush operations to all cells, only land cells, or only water cells. This prevents accidental coastline changes or new landmass creation while editing ocean depths, and vice versa.

src/index.html

• Replaced the two separate changeOnlyLand and changeOnlyOcean checkboxes with a single <select id="cellTypeFilter"> dropdown offering three options: all cells (default), only land cells, and only water cells

public/modules/ui/heightmap-editor.js

• Mode switching — sets cellTypeFilter.value on mode change: keep mode selects "land", erase/risk modes reset to "all"
• updateHeightmap() — safety rollback reverts cells that crossed the h=20 land/water boundary based on the active filter
• dragBrush() — pre-filters brush selection to land (h >= 20) or water (h < 20) cells depending on the selected filter
• placeLinearFeature() — skips land or water cells based on the active filter
• changeHeightForSelection() — lim bounds adjusted per filter (min=20 for land-only, max=19 for water-only); brushRaise skips the ocean-to-land jump in water-only mode; brushSmooth neighbor filter respects the active filter
• rescale() — skips out-of-filter cells and clamps output to the appropriate range
• startFromScratch() — blocked when any non-"all" filter is active
• cellTypeFilterChange() — new handler that prevents selecting "land" filter in keep edit mode

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[Azgaar]

@copilot, replace two checkboxes with a select input with 'check all cells', 'check only land cells' and 'check only water cells' options.

[Azgaar]

replace two checkboxes with a select input with 'check all cells', 'check only land cells' and 'check only water cells' options.

[Copilot]

@copilot, replace two checkboxes with a select input with 'check all cells', 'check only land cells' and 'check only water cells' options.

Done in 1edb1e2. The two checkboxes are replaced with a single cellTypeFilter select in the brush panel with three options: all cells, only land cells, and only water cells. All brush operations, rescaler, and startFromScratch are updated to read from this select. The 'Keep' edit mode continues to auto-select "only land cells" and blocks switching to anything else via the change handler.

[Copilot]

Pull request overview

This PR updates the heightmap editor brush UI to use a single cellTypeFilter dropdown, letting users restrict edits to all cells, land-only, or water-only, to reduce accidental coastline changes during height editing.

Changes:

• Replaces prior cell-type restriction checkboxes with a single cellTypeFilter <select> in the brush panel UI
• Updates heightmap brush/line editing logic to honor the selected cell-type filter (including some safety rollback and rescale behavior)

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/index.html	Replaces the previous checkbox UI with a cellTypeFilter dropdown
public/modules/ui/heightmap-editor.js	Wires the new filter into brush/line operations, rescale, and mode switching

[Copilot]

cellTypeFilterChange currently blocks selecting the "land" filter in "keep" mode and resets to "all". In "keep" mode the UI copy says the coastline cannot change, which requires forcing a land-only constraint (matching enterHeightmapEditMode setting cellTypeFilter.value = "land"). Consider preventing changes away from "land" while in keep mode (e.g., revert to "land" / disable the select) rather than rejecting the land option.

Suggested change

	if (cellTypeFilter.value === "land" && heightmapEditMode.innerHTML === "keep") {
	tip("You cannot change the coastline in 'Keep' edit mode", false, "error");
	cellTypeFilter.value = "all";
	if (heightmapEditMode.innerHTML === "keep" && cellTypeFilter.value !== "land") {
	tip("You cannot change the coastline in 'Keep' edit mode", false, "error");
	cellTypeFilter.value = "land";

[Copilot]

In placeLinearFeature, the cell-type filter checks heights[i] (the pre-operation height) to decide whether to apply changedHeights[i]. This allows coastline changes to slip through (e.g., a land cell can be lowered below 20 in land-only mode, or a water cell raised above 19 in water-only mode), and this path doesn't call updateHeightmap() so the rollback logic won't correct it. Filter/clip based on the resulting height (changedHeights[i]) and/or reuse the same limiting logic used by brush editing, or call updateHeightmap() after applying the changes.