skill: add Android skills

.agents/skills/agp-9-upgrade/references/paparazzi-gradle-9.md

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+If Paparazzi is used in the project, update it to version 2.0.0-alpha04 or
+higher.
+
+Paparazzi version 2.0.0-alpha04 and lower is not fully compatible with Gradle
+9, and Gradle 9 is required by AGP 9. This means that, without workarounds,
+projects that use Paparazzi v2.0.0-alpha04 and lower cannot migrate to AGP 9.
+
+At time of writing, there are no higher versions of Paparazzi. That is,
+v2.0.0-alpha04 is the latest release.
+
+The issue is due to Paparazzi using internal classes from Gradle that tend to
+move in breaking ways without warning. This specific issue is related to HTML
+test reports. To work around it, disable those HTML test reports. Here
+are two examples of how to do this, one for Kotlin DSL and the other for Groovy
+DSL. Any module that has the paparazzi plugin (`app.cash.paparazzi`) applied
+must apply one of these two workarounds.
+
+Kotlin DSL:
+
+    tasks.withType<Test>().configureEach {
+      // https://github.com/cashapp/paparazzi/issues/2111
+      reports.html.required = false
+    }
+
+Groovy DSL:
+
+    tasks.withType(Test).configureEach {
+      // https://github.com/cashapp/paparazzi/issues/2111
+      reports.html.required = false
+    }