[low] fix: [wifi_geolocation_kml] gx: prefix is used but never declared, so every KML is not namespace-well-formed

[elhoim]

BLUF

• Priority: low in scope, but the output is completely unusable, not merely imperfect: every KML this analyser has ever produced fails to parse.
• The gx: prefix is used but never declared. The root element declares only the default KML namespace, while five elements below use gx: — gx:Tour, gx:Playlist, gx:FlyTo, gx:duration, gx:flyToMode.
• This is not a validation nicety — it is a well-formedness error. An undeclared namespace prefix makes the document malformed, so a conforming parser refuses it outright. xml.etree.ElementTree.fromstring() on the current output raises ParseError: unbound prefix: line 2, column 54.
• ElementTree will not catch this on the writing side. It treats "gx:Tour" as an opaque tag name and serialises it verbatim, so generation succeeds silently and the failure only appears when something tries to read the file — Google Earth, a KML library, or an analyst's own tooling.
• Fix: declare xmlns:gx="http://www.google.com/kml/ext/2.2" — the standard Google KML extension namespace that these elements belong to — on the root element.
• Scope: one element construction in wifi_geolocation_kml.py, plus a regression test.

Before

<kml xmlns="http://www.opengis.net/kml/2.2"><Document><gx:Tour>...

xml.etree.ElementTree.ParseError: unbound prefix: line 2, column 54

After

<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2"><Document><gx:Tour>...

Parses cleanly; root tag resolves to {http://www.opengis.net/kml/2.2}kml.

Test

test_generated_kml_is_namespace_well_formed generates a KML from a one-network input and runs ET.fromstring() over it, asserting the root tag resolves in the KML namespace and the gx namespace URI is present.

Verified to fail on main with ParseError: unbound prefix and pass with this change. The existing test_analyse_wifi_geolocation_kml only asserts the output file is non-empty, so it is unaffected.