Phase 2: API keys encrypted with the vault

app/src/main/java/io/github/abrarul/modularai/security/SecretStore.kt

@@ -0,0 +1,11 @@
+package io.github.abrarul.modularai.security
+
+import android.content.Context
+
+/** Stores API keys as Vault ciphertext in private SharedPreferences. */
+class SecretStore(ctx: Context) {
+    private val p = ctx.getSharedPreferences("secrets", Context.MODE_PRIVATE)
+    fun put(name: String, value: String) = p.edit().putString(name, Vault.encrypt(value)).apply()
+    fun get(name: String): String? = p.getString(name, null)?.let { runCatching { Vault.decrypt(it) }.getOrNull() }
+    fun wipe() = p.edit().clear().apply()
+}