fix(parser): key style map by referenceable id only

[danielebarbaro]

Problem

Anonymous styles overwrite each other

getStyles() runs //kml:Style and indexes every match by its id attribute:

$id = (string) $styleXml->attributes()->id;
// ...
$styles[$id] = $style;

That XPath also matches the <Style> elements declared inline inside a Placemark, which have no id. Every one of them casts to '', so they all land on the same key and silently overwrite each other. A document with ten inline styles produces one entry under '' holding whichever came last.

Inline styles cannot be referenced through a styleUrl in the first place, so having them in a map keyed by id serves no purpose.

Dead ->n fallbacks

'name' => (string) ($placemarkXml->name ?: $placemarkXml->n),

and the matching $document[0]->n branch in getDocumentName(). n is not a KML element; these look like the residue of a bad find/replace. Unreachable for any valid document.

Fix

• Skip Style elements without an id in getStyles(), so the returned map contains only shared, referenceable styles.
• Remove both ->n fallbacks.

Tests

tests/StyleAndNameExtractionTest.php, against a document with two shared styles and two anonymous inline ones:

• regression test (fails on main): only the two id-bearing styles are returned, no '' key, and each keeps its own scale. On main this returns 3 entries, one of which is the clobbered '' bucket.
• two guards confirming the name reading still works after dropping the ->n branches.

To be explicit about scope: the ->n removal is dead-code cleanup, not a live bug fix. The two name tests pass on main too; they are there so the removal is covered, not to demonstrate a defect.

Behaviour change

getStyles() no longer returns an entry under the '' key. Anything relying on that key was reading a single arbitrary inline style out of however many the document contained, so this is a correction rather than a loss of capability. Worth a note in the changelog.

Notes

Includes a one-line Pint fix in loadFromString() (\Exception -> Exception), since src/KmlParser.php fails pint --test on main and this PR touches the file.