fix(ui): drop {loc}/{time} placeholders when naming a radio preset

The shared on-screen keyboard seeds {loc}/{time} placeholders on begin()
for message composition, but they make no sense in a radio-preset name.
Clear them right after opening the keyboard from the "+ Save current..."
flow in both Settings > Radio and Tools > Repeater; the message-slot
editor still keeps them.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

examples/companion_radio/ui-new/RepeaterScreen.h

@@ -188,6 +188,7 @@ public:
         switch (_picker.onSelected(_picker.menu.selectedIndex(), p, rptTarget(p))) {
           case RadioPresetPicker::START_SAVE:
             _task->keyboard().begin("", (int)sizeof(p->user_radio_presets[0].name) - 1);
+            _task->keyboard().clearPlaceholders();   // {loc}/{time} are for messages, not preset names
             break;
           case RadioPresetPicker::APPLIED:
             the_mesh.applyRepeaterRadio();   // live if currently relaying on the profile

examples/companion_radio/ui-new/SettingsScreen.h

@@ -732,6 +732,7 @@ public:
         switch (_picker.onSelected(_picker.menu.selectedIndex(), p, radioTarget(p))) {
           case RadioPresetPicker::START_SAVE:
             _kb->begin("", (int)sizeof(p->user_radio_presets[0].name) - 1);
+            _kb->clearPlaceholders();   // {loc}/{time} are for messages, not preset names
             break;
           case RadioPresetPicker::APPLIED:
             _task->applyRadioParams();