fix(ux): selected text visible in user message bubbles + CI i18n fix — v0.50.160 (PR #877 by @pavolbiely)

User bubble selection contrast fixed via scoped ::selection CSS (closes #877). Also adds missing provider i18n keys to es/de/zh/ru/zh-Hant locales, fixing 3 CI failures that crept in from PR #867.

tests/test_bugbatch_apr2026.py

@@ -76,6 +76,29 @@ def test_dark_user_bubbles_do_not_need_per_skin_text_hacks():
     )
 
 
+def test_user_bubbles_define_selection_tokens_for_both_modes():
+    """User bubbles need dedicated selection colors so selected text remains readable."""
+    assert "--user-selection-bg: rgba(0,0,0,.22);" in STYLE_CSS, (
+        "Light-mode user bubbles should define a darker selection fill for contrast"
+    )
+    assert "--user-selection-bg: rgba(255,255,255,.18);" in STYLE_CSS, (
+        "Dark-mode user bubbles should define a lighter selection fill for contrast"
+    )
+    assert "--user-selection-text: #fff;" in STYLE_CSS, (
+        "Light-mode user bubble selection should preserve readable text color"
+    )
+
+
+def test_user_bubble_selection_is_scoped_to_user_message_body():
+    """Selection override must apply only to user bubbles, including nested markdown nodes."""
+    assert '.msg-row[data-role="user"] .msg-body::selection,' in STYLE_CSS, (
+        "Missing selection override on the user message bubble"
+    )
+    assert '.msg-row[data-role="user"] .msg-body *::selection {' in STYLE_CSS, (
+        "Nested elements inside user messages must inherit the same selection colors"
+    )
+
+
 # ── #576: workspace panel snap fix ───────────────────────────────────────────
 
 def test_576_panel_restore_gated_on_workspace():