feat: Enhance architecture and performance optimizations

- Updated architecture documentation to reflect changes in data layer and caching strategies.
- Implemented LRU caching for key pair generation and private key hash to improve performance.
- Refactored DatabaseService to include LRU caching for encrypted accounts, reducing database query times.
- Introduced a search bar in SelectAccountScreen for filtering accounts, enhancing user experience.
- Adjusted UI components for better spacing and consistency.
- Updated build.gradle.kts to support Java 17 and Room incremental annotation processing.
- Modified gradle.properties to include necessary JVM arguments for Java 17 compatibility.

app/src/main/java/com/rosetta/messenger/database/DatabaseService.kt

@@ -172,7 +172,10 @@ class DatabaseService(context: Context) {
                 CryptoManager.decryptWithPassword(
                     encryptedAccount.privateKeyEncrypted,
                     password
-                )
+                ) ?: run {
+                    Log.e(TAG, "❌ Failed to decrypt private key - returned null")
+                    return@withContext null
+                }
             } catch (e: Exception) {
                 Log.e(TAG, "❌ Failed to decrypt private key - wrong password?", e)
                 return@withContext null
@@ -183,7 +186,10 @@ class DatabaseService(context: Context) {
                 CryptoManager.decryptWithPassword(
                     encryptedAccount.seedPhraseEncrypted,
                     password
-                )
+                ) ?: run {
+                    Log.e(TAG, "❌ Failed to decrypt seed phrase - returned null")
+                    return@withContext null
+                }
             } catch (e: Exception) {
                 Log.e(TAG, "❌ Failed to decrypt seed phrase - wrong password?", e)
                 return@withContext null