fix(nix): share Gradle home so worktree daemons stop piling up (#1339)

flake.nix

@@ -76,8 +76,9 @@
           ANDROID_SDK_ROOT = "${androidSdk}/libexec/android-sdk";
           JAVA_HOME = "${pkgs.jdk21}";
 
-          # Gradle needs a writable home
-          GRADLE_USER_HOME = "$PWD/.gradle-home";
+          # GRADLE_USER_HOME stays at the default ~/.gradle: Nix attrs are not
+          # shell-expanded, so "$PWD/..." gave every checkout and worktree its
+          # own cache and daemon pool, and idle daemons piled up in RAM.
 
           shellHook = ''
             echo " HermesControl Android dev shell"
@@ -90,9 +91,6 @@
             # Ensure Android CLI tools and local user binaries are on PATH
             export PATH="$ANDROID_HOME/platform-tools:$ANDROID_HOME/emulator:$HOME/.local/bin:$PATH"
 
-            # Writable gradle home
-            mkdir -p "$GRADLE_USER_HOME"
-
             # Enable host keyboard input for the project's existing AVD.
             hermesAvdConfig="''${ANDROID_AVD_HOME:-''${ANDROID_USER_HOME:-$HOME/.android}/avd}/hermes_dev.avd/config.ini"
             if [ -f "$hermesAvdConfig" ]; then

gradle.properties

@@ -7,6 +7,8 @@
 # Specifies the JVM arguments used for the daemon process.
 # The setting is particularly useful for tweaking memory settings.
 org.gradle.jvmargs=-Xmx2048m -Dfile.encoding=UTF-8
+# Stop idle daemons after 20 min (default 3 h) so finished builds release their RAM.
+org.gradle.daemon.idletimeout=1200000
 # Enables Gradle Build Cache.
 # See https://docs.gradle.org/current/userguide/build_cache.html
 org.gradle.caching=true