sources: Add initial UI

data/icons/heroic-symbolic.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="none"><path fill="#000" fill-rule="evenodd" d="m7.872 16-3.817-3.083L2 2.79 7.872 0l5.871 2.789-2.055 10.128zm0-4.257-.294-.293-.88-7.927 1.1-1.908 1.174 1.908-.807 7.927zm-.294.367-.147.367-1.761.294-.294-.66.294-.662 1.761.294zm-.073.734-.22 1.541.587.294.587-.294-.22-1.541-.367-.22zm.807-.367-.147-.367.147-.367 1.761-.293.294.66-.294.66z" clip-rule="evenodd"/></svg>

data/icons/icons.gresource.xml.in

@@ -4,6 +4,10 @@
     <file>apply-symbolic.svg</file>
     <file>cancel-symbolic.svg</file>
     <file>filter-symbolic.svg</file>
+    <!-- Sources -->
+    <file>heroic-symbolic.svg</file>
+    <file>imported-symbolic.svg</file>
+    <file>steam-symbolic.svg</file>
     <!-- Categories -->
     <file>collection-symbolic.svg</file>
     <file>ball-symbolic.svg</file>

data/icons/imported-symbolic.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 16 16"><path fill="#222" d="M7 1v6H1v2h6v6h2V9h6V7H9V1zm0 0"/></svg>

data/icons/steam-symbolic.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" fill="none"><g clip-path="url(#a)"><path fill="#000" fill-rule="evenodd" d="M9.352 5.1a1.509 1.509 0 1 0 2.51 1.675A1.509 1.509 0 0 0 9.352 5.1m2.923-.277a2.009 2.009 0 1 1-3.34 2.231 2.009 2.009 0 0 1 3.34-2.23ZM5.01 12.131l-.983-.407a1.7 1.7 0 0 0 3.108-.103 1.696 1.696 0 0 0-1.213-2.29 1.7 1.7 0 0 0-.966.07l1.015.421a1.249 1.249 0 0 1-.96 2.307zM2.546 2.121A8 8 0 0 1 7.966 0l.003.013a7.99 7.99 0 0 1 7.159 4.432 7.996 7.996 0 0 1-4.277 11.018 7.99 7.99 0 0 1-8.274-1.558A8 8 0 0 1 .279 10.18l3.064 1.267A2.264 2.264 0 0 0 7.823 11v-.107l2.718-1.938h.063A3.016 3.016 0 1 0 7.589 5.94v.031l-1.906 2.76h-.126c-.454 0-.898.138-1.273.395L0 7.354A8 8 0 0 1 2.546 2.12Z" clip-rule="evenodd"/></g><defs><clipPath id="a"><path fill="#fff" d="M0 0h16v16H0z"/></clipPath></defs></svg>