Add geospatial filter modal to query builder

[sharppaul]

A query could only get an area filter after a run on the map viewer.
The modal draws one in the builder, before the first run.

The area now carries the two columns it tests. The compile resolved
that pair by name detection alone, so a table with x/y columns could
not take an area. The user picks the pair in the modal, and detection
stays the fallback.

Addresses issue #82

[Copilot]

🟡 Changes recommended

It introduces a validated-column flow but still allows an invalid same-column pair in selection resolution and has formatting issues that can break tooling.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

This pull request adds a geospatial filter modal to the query builder so users can draw an area filter before the first map run. It also updates spatial-filter compilation and hydration so the filter uses the user-selected coordinate column pair, with name-based detection as a fallback.

Changes:

• Add a builder modal that renders a basemap and draw tools to create or edit a spatial filter.
• Persist the chosen coordinate column pair on the spatial selection and resolve it via selectionColumns() during compile and map edits.
• Improve dialog/modal sizing and scrolling behavior to keep modal content usable on smaller viewports.

File summaries

File	Description
src/tailwind.css	Define --color-background so bg-background works correctly in dialogs.
src/routes/visualisations/map-viewer/+page.svelte	Preserve and restamp selected coordinate columns when applying a redrawn area.
src/lib/query/seed-hydration.ts	Match derived bbox filters using the exact stored coordinate column names.
src/lib/query/draft.ts	Compile spatial filters using selectionColumns() instead of coordinate detection alone.
src/lib/geo/spatial-selection.ts	Store selected coordinate columns on selections and add helpers to resolve and validate them.
src/lib/components/visualisation/SpatialFilterMap.svelte	New lightweight MapLibre basemap component for drawing areas without data layers.
src/lib/components/visualisation/MapDrawTools.svelte	Add optional “Apply” button rendering and harden cleanup on destroy.
src/lib/components/ui/dialog/dialog-content.svelte	Constrain dialog size to viewport and enable scrolling for overflow content.
src/lib/components/query-builder/QueryWorkspace.svelte.ts	Update spatial filter patching for blocks without drafts, using stored column pairs.
src/lib/components/query-builder/QueryBuilderParameterBlock.svelte	Add geospatial filter UI entry points and wire the new modal into the builder.
src/lib/components/query-builder/GeospatialFilterModal.svelte	New modal to select coordinate columns and draw/apply/remove an area filter.
src/lib/components/modals/Modal.svelte	Make Escape-close respect live canCloseModal and add scrolling layout constraints.
AGENTS.md	Document the new “selection carries coordinate columns” rule and remove an outdated note.

Review details

• Files reviewed: 13/13 changed files
• Comments generated: 3
• Review effort level: Lite

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[Copilot]

🟢 Approval recommended

The functional changes are cohesive and low-risk, with only minor user-facing text and spelling nits noted.

Review details

Suppressed comments (4)

Previously missed (2) — in code that hasn't changed since the last review.

src/lib/components/query-builder/GeospatialFilterModal.svelte:100

• Update this message. The check uses the count of number columns, not the column names.

This issue also appears on line 149 of the same file.
src/lib/components/query-builder/QueryBuilderParameterBlock.svelte:3

• Fix spelling in the file header comment. The filename is misspelled as "QueryBuilderParametrBlock.svelte".

This issue also appears on line 131 of the same file.

src/lib/components/query-builder/QueryBuilderParameterBlock.svelte:134

• Update this hint text. The code checks for two number columns, not only columns named latitude and longitude.

	const areaBlockReason = $derived.by(() => {
		if (numericColumnCount < 2) {
			return 'Select a latitude and a longitude column first.';
		}

src/lib/components/query-builder/GeospatialFilterModal.svelte:150

• Update this warning text. It mentions latitude and longitude names, but the constraint is only two number columns.

					This query selects less than two number columns. Add a latitude and a longitude column
					first.

• Files reviewed: 13/13 changed files
• Comments generated: 0 new
• Review effort level: Lite