fix(settings): accept dictionary source URLs over https only

The platform blocks cleartext traffic by default, so an http:// source
passed validation but could never download and failed with a misleading
network error. The validator now rejects http:// upfront.

app/src/main/java/com/example/research/core/domain/model/DictionarySource.kt

@@ -106,7 +106,7 @@ data class DictionarySource(
             return when {
                 trimmed.isBlank() -> ValidationResult.Error(ValidationError.EMPTY)
                 trimmed.length > 2048 -> ValidationResult.Error(ValidationError.TOO_LONG)
-                !trimmed.startsWith("http://") && !trimmed.startsWith("https://") ->
+                !trimmed.startsWith("https://") ->
                     ValidationResult.Error(ValidationError.INVALID_PROTOCOL)
                 !lowerTemplate.endsWith(".gz") &&
                     !lowerTemplate.endsWith(".dsl") &&

app/src/main/res/values-ru/strings.xml

@@ -76,7 +76,7 @@
     <string name="dictionary_source_duplicate_in_form">Дублирующийся URL в форме</string>
     <string name="dictionary_source_duplicate_prefix">Этот словарь уже существует (одинаковый префикс)</string>
     <string name="dictionary_source_url_empty">URL не может быть пустым</string>
-    <string name="dictionary_source_invalid_protocol">Должен начинаться с http:// или https://</string>
+    <string name="dictionary_source_invalid_protocol">Должен начинаться с https://</string>
     <string name="dictionary_source_invalid_extension">Должен заканчиваться на .gz, .dsl или .dsl.dz</string>
     <string name="dictionary_source_too_long">URL слишком длинный (максимум 2048 символов)</string>
     <string name="dictionary_source_invalid_url">Неверный формат URL</string>

app/src/main/res/values/strings.xml

@@ -74,7 +74,7 @@
     <string name="dictionary_source_duplicate_in_form">Duplicate URL in the form</string>
     <string name="dictionary_source_duplicate_prefix">This dictionary already exists</string>
     <string name="dictionary_source_url_empty">URL cannot be empty</string>
-    <string name="dictionary_source_invalid_protocol">Must start with http:// or https://</string>
+    <string name="dictionary_source_invalid_protocol">Must start with https://</string>
     <string name="dictionary_source_invalid_extension">Must end with .gz, .dsl, or .dsl.dz</string>
     <string name="dictionary_source_too_long">URL is too long (max 2048 characters)</string>
     <string name="dictionary_source_invalid_url">Invalid URL format</string>