feat(ios): add Russian locale (#1964)

* feat(ios): add Russian locale

Add Russian translations to Localizable.xcstrings for all 591 catalog
entries (reusing matching Android translations and translating the rest);
zh-Hans and format placeholders are preserved.

* fix(ios): make Russian selectable and use correct plural forms

- add AppLanguage.russian ("ru"), its display name, the AppleLanguages
  override, and register ru in the Xcode project's knownRegions so the
  language picker can actually select Russian
- add Russian one/few/many/other plural variations for %lld sessions,
  %lld attachments and %@, %lld sessions
- use count-agnostic phrasing for the other dynamic counts (tools, edits,
  lines, chars, findings, notes, queued messages, questions, ...)
- correct Input/Output to Ввод/Вывод
- cover the new language case in ThemePrefsTests

* fix(ios): use Russian plural forms for the remaining count labels

* fix(ios): pass the step count to the plural localization

* fix(ios): pass tool counts to the plural localization

* fix(ios): keep the singular English tool-group labels

---------

Co-authored-by: mrudy <mrudy@local>

ios/Hapi/Features/Chat/Blocks/ToolCallBlockView.swift

@@ -48,7 +48,7 @@ struct ToolCallBlockView: View {
             if opensToolProcess(block) {
                 Button { openTool?(block) } label: {
                     Label(
-                        String(format: String(localized: "View process · %lld steps"), Int64(block.children.count)),
+                        String(localized: "View process · \(block.children.count) steps"),
                         systemImage: "arrow.right"
                     )
                     .font(typography.captionFont)