Fix all Play Store blocking issues in Android app

[DaLuSt]

Client ID — no longer hardcoded in build.gradle

• build.gradle reads reddit.client_id from local.properties (gitignored)
• Falls back to placeholder so the build never breaks without the file
• Developers set it once in local.properties; no build file edits needed

Release signing

• Added signingConfigs.release that reads storeFile / storePassword / keyAlias / keyPassword from keystore.properties (gitignored)
• Added buildTypes.release with signingConfig signingConfigs.release
• Added buildTypes.debug with .debug applicationId suffix
• Updated .gitignore: keystore.properties, *.jks, *.keystore

ProGuard / R8

• Release build sets minifyEnabled=true and shrinkResources=true
• Created proguard-rules.pro with rules for Retrofit, OkHttp, Gson, Kotlin, EncryptedSharedPreferences, and the app's own model/api packages

Adaptive app icon (minSdk 26 — no PNGs required)

• res/drawable/ic_launcher_background.xml — Reddit-orange (#FF4500) fill
• res/drawable/ic_launcher_foreground.xml — white trash-can icon scaled to the 72×72dp adaptive safe zone inside the 108×108dp canvas
• res/mipmap-anydpi-v26/ic_launcher.xml and ic_launcher_round.xml
• AndroidManifest now references @mipmap/ic_launcher and roundIcon

Network security config

• res/xml/network_security_config.xml — cleartextTrafficPermitted=false, trust system CAs only (no user-installed CAs)
• AndroidManifest references @xml/network_security_config

Privacy policy

• android/PRIVACY_POLICY.md — covers scopes, local storage, data-not-collected, and Reddit API third-party disclosure
• SETUP.md updated with Play Store listing checklist (host policy URL)

Bonus fixes (important tier, trivially co-located)

• Removed unused vote scope from OAUTH_SCOPES
• Downgraded security-crypto from alpha 1.1.0-alpha06 → stable 1.0.0
• RedditApiClient: logging interceptor now NONE in release, BASIC in debug
• RedditApiClient: replaced tokenStorage.refreshToken!! with safe local val to eliminate potential NullPointerException on race condition
• AndroidManifest: allowBackup changed from true to false (tokens are sensitive; backup of EncryptedSharedPreferences is unnecessary)
• SETUP.md: full release build walkthrough added (keytool, keystore.properties, bundleRelease); project structure table updated; vote scope removed

https://claude.ai/code/session_014HLhrFtCVRFnEyfRexiy3d