The Blade extractor recognised @include, <livewire:> components, and
wire:click bindings, but not @extends. Template inheritance is the primary
structural relationship in a Blade view — most page templates render inside
a layout via @extends('layouts.app') — so the child was left with no edge
to its parent layout in the graph.
Emit an 'extends' edge from the view to the named layout, mirroring the
existing @include handling (dotted view name -> path). Adds the first test
coverage for the Blade extractor.
(cherry picked from commit efeeeefa53)