fix(map) :: ignore map coordinates that are not a pair of numbers

[81reap]

Motivation

• parseCoords returns whatever Number.parseFloat gives it, so "48.8" becomes [48.8] and "north" becomes [NaN].
• Leaflet rejects such a value, and the exception stops the map being built, so one bad row hides every other marker.

Description

• parseCoords returns undefined unless it parsed exactly two finite numbers.
• createMarker returns undefined for a marker it cannot place, and the caller skips it.
• Add tests/end-to-end/map-component.spec.ts, covering a well-formed centre and marker, a centre and a marker with no longitude, and a centre that is not numeric at all.
• Add a changelog entry.

Testing

• The browser suite passes 26 tests, five of them new.
• The new tests assert that the other markers still appear when one is dropped.
• npm test checks 37 files and reports nothing.
• no console errors on card page fails for the reason described in fix(biome.js) :: fix remaining lint issues #1366, on this branch and on the unmodified base alike.

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GitHub cannot base a pull request on a branch that lives in a fork, so all eight target main and each one carries the commits of those above it. Review and merge them in order:

1. fix(biome.js) :: fix remaining lint issues #1366 :: fix(biome.js) :: fix remaining lint issues
2. fix(modal) :: give modal component an accessible name #1367 :: fix(modal) :: give modal component an accessible name
3. fix(map) :: ignore map coordinates that are not a pair of numbers #1368 :: fix(map) :: ignore map coordinates that are not a pair of numbers ← this PR
4. feat(chart) :: render column charts as bar charts #1369 :: feat(chart) :: render column charts as bar charts
5. fix(chart) :: align stacked series on their X values #1370 :: fix(chart) :: align stacked series on their X values
6. fix(chart) :: line series up on a category axis for every chart type #1371 :: fix(chart) :: line series up on a category axis for every chart type
7. fix(npm) :: install dependencies only once at root level #1372 :: fix(npm) :: install dependencies only once at root level
8. feat(typescript) :: typecheck browser JavaScript in CI #1373 :: feat(typescript) :: typecheck browser JavaScript in CI