Parse custom_recovery_passphrase_settings from Element .well-known

Add CustomRecoveryPassphraseRequirements to ElementWellKnown and decode
the custom_recovery_passphrase_settings block (currently just
min_character_count) from the homeserver's element.json. Invalid specs
(missing or non-positive min_character_count) are logged and mapped to
null so the setup flow falls back to the generated-key path. Field names
match the ESS well-known schema (element-enterprise#261).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

libraries/wellknown/api/src/main/kotlin/io/element/android/libraries/wellknown/api/CustomRecoveryPassphraseRequirements.kt

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2026 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.wellknown.api
+
+/**
+ * Server-driven requirements for a user-chosen recovery passphrase. Today the only rule
+ * is a minimum character count; additional rules can be added here as the well-known
+ * schema (`custom_recovery_passphrase_settings`) grows.
+ */
+data class CustomRecoveryPassphraseRequirements(
+    val minCharacterCount: Int,
+) {
+    /** True when [input] meets every active rule. */
+    fun isSatisfiedBy(input: String): Boolean = isSatisfiedBy(input.length)
+
+    /** True when an input of [length] characters meets every active rule. */
+    fun isSatisfiedBy(length: Int): Boolean = length >= minCharacterCount
+}

libraries/wellknown/api/src/main/kotlin/io/element/android/libraries/wellknown/api/ElementWellKnown.kt

@@ -15,4 +15,5 @@ data class ElementWellKnown(
     val brandColor: String?,
     val notificationSound: String?,
     val identityProviderAppScheme: String?,
+    val customRecoveryPassphraseRequirements: CustomRecoveryPassphraseRequirements?,
 )