Initial commit: Kecalek Android client

Complete Android client for encrypted chat platform.
78+ Kotlin files: crypto (X3DH, Double Ratchet, AES-GCM, Ed25519, X25519,
RSA-PSS), network (TCP/TLS, 50 endpoints), Hilt DI, Room+SQLCipher DB,
Jetpack Compose UI with Catppuccin Mocha theme.

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

app/proguard-rules.pro

@@ -0,0 +1,10 @@
+# Bouncy Castle
+-keep class org.bouncycastle.** { *; }
+-dontwarn org.bouncycastle.**
+
+# Tink
+-keep class com.google.crypto.tink.** { *; }
+
+# SQLCipher
+-keep class net.sqlcipher.** { *; }
+-keep class net.sqlcipher.database.** { *; }