[BUG] `Button::setTooltip` is a no-op; power button tooltips never display

[brianhelba]

Submission checklist

• I have searched existing issues and confirmed this is not a duplicate.
• I am using the latest available version of noctalia-greeter.

Bug description

Button::setTooltip is an empty stub (src/ui/controls/button.cpp:323), unchanged since the initial commit.

Callers set tooltip text, e.g. the power buttons ("Shut down", "Restart", "Restart to UEFI firmware setup") in greeter_surface.cpp:521-528 and the synced power-action labels (greeter_surface.cpp:531-546), but the text is never rendered.

Steps to reproduce

1. At the greeter, hover any power button (or focus it with Tab)
2. Wait
3. No tooltip appears

Expected behavior

The tooltip text set on the button ("Shut down", "Restart", "Restart to UEFI firmware setup") is shown on hover/focus.

Actual behavior

No tooltip is rendered for any button; Button::setTooltip discards the text.

Logs / error output

noctalia-greeter version

v1.2.1

Distribution

Arch-based

Environment information

Installation method: CachyOS official repo package (noctalia-greeter 1.1.0-1), then local build 1.2.1
greetd user: greeter
GPU: Intel Iris Xe, Alder Lake-P GT2 (i915)
Monitor setup: single internal eDP-1 (3456x2160)
greeter.toml: only [session].default, [idle].timeout, [cursor] set; not relevant to this issue

Additional context

No response