fix: migrate Google Places Autocomplete to PlaceAutocompleteElement (closes #161)

[erdem]

Summary

• Replaces deprecated google.maps.places.Autocomplete with google.maps.places.PlaceAutocompleteElement
• Fixes place selection not placing a marker on the map
• Updates default Google Maps API version from quarterly to beta (required for PlaceAutocompleteElement)

Changes

mw_pointfield.js

• initializePlaceAutocomplete: creates PlaceAutocompleteElement, replaces the existing <input> in-place (preserving class/placeholder), and binds map bounds via locationBias
• Event listener changed from deprecated gmp-placeselect → gmp-select; place is accessed via placePrediction.toPlace() + fetchFields(['location', ...])
• Removed handleAutoCompletePlaceChange and handleAutoCompleteInputKeyDown (handled internally by the web component)
• Removed leftover debug console.log calls

mw_pointfield_base.js

• resetMap uses elem.value = "" instead of $(elem).val("") to support the PlaceAutocompleteElement web component

settings.py

• Default CDNURLParams.v changed from "quarterly" to "beta" — PlaceAutocompleteElement is only available in the beta channel

Minified files regenerated to match.

Closes #161