build: add consumer-rules.pro and untrack local.properties

consumer-rules.pro was referenced in all modules but never committed;
Gradle fails if the declared proguard file doesn't exist on disk.
local.properties is machine-specific (sdk.dir) and must not be in VCS.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitignore

@@ -12,3 +12,4 @@ build/
 # Sentry Config File
 sentry.properties
 /.gradle-home/
+local.properties

local.properties

@@ -1,8 +0,0 @@
-## This file must *NOT* be checked into Version Control Systems,
-# as it contains information specific to your local configuration.
-#
-# Location of the SDK. This is only used by Gradle.
-# For customization when using a Version Control System, please read the
-# header note.
-#Wed Apr 22 12:00:36 CST 2026
-sdk.dir=/Users/xuqinmin/Library/Android/sdk