feat: percentage-based container sizing with live boundary resize

- Windows are sized as ratios of their container; new windows get 1/n
  and existing windows scale proportionally
- Boundaries can be dragged live; resize is clamped only to prevent
  pane inversion (no minimum ratio enforced)
- Add reset-ratios keybinding to equalize splits in the active container
- Collapse duplicate logic, remove dead code, clean up prefs and schema

schemas/org.gnome.shell.extensions.aerospike.gschema.xml

@@ -49,5 +49,11 @@
             <description>Toggles the orientation of the container holding the active window between horizontal and vertical</description>
         </key>
 
+        <key name="reset-ratios" type="as">
+            <default><![CDATA[['<Primary>z']]]></default>
+            <summary>Reset container ratios to equal splits</summary>
+            <description>Resets all window size ratios in the active window's container to equal splits</description>
+        </key>
+
     </schema>
 </schemalist>