feat(chat): integrate fast mode toggle into generation controls dropdown (#1093)

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

@@ -1158,6 +1158,9 @@
     <string name="channels_expiry_format">Expires: %1$s</string>
     <string name="channels_search_placeholder">Search channels…</string>
     <string name="chat_attach_file">Attach file</string>
+    <string name="chat_fast_mode_label">Fast</string>
+    <string name="chat_fast_mode_desc">Fast mode</string>
+    <string name="chat_fast_mode_unavailable">Fast mode unavailable for this model</string>
     <string name="chat_save_attachment">Save %1$s</string>
     <string name="chat_switch_model_title">Switch model (this chat)</string>
     <string name="config_clear_value">Clear value</string>