v1.18: center the tank + driver in the launcher icon

The subject was filling the frame edge-to-edge, so launcher masking
clipped the gun barrel, treads, and the driver. Auto-detect the tank+bot
(erode away the debris specks, take that bbox), recenter on a square
canvas at ~74% with matching navy #0B1D27 margin so the whole subject
stays inside any mask shape. Regenerated all densities + icon.png.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/build.gradle.kts

@@ -11,8 +11,8 @@ android {
         applicationId = "me.khodak.claudeusage"
         minSdk = 26
         targetSdk = 34
-        versionCode = 18
+        versionCode = 19
-        versionName = "1.17"
+        versionName = "1.18"
     }
 
     signingConfigs {

app/src/main/res/values/colors.xml

@@ -5,5 +5,5 @@
     <color name="surface_dark">#1E1E1E</color>
     <color name="text_primary">#FFFFFF</color>
     <color name="text_secondary">#888888</color>
-    <color name="ic_launcher_bg">#16222B</color>
+    <color name="ic_launcher_bg">#0B1D27</color>
 </resources>