Hold power profile through power-profiles-daemon

[caniko]

Summary

Use the power-profiles-daemon HoldProfile API while GameMode is active.

The first registered client requests the configured performance profile, and the final client releases it. The system D-Bus connection remains open for the lifetime of the hold, so daemon exit also releases it.

Behavior

• Prefer org.freedesktop.UPower.PowerProfiles.
• Fall back to the legacy net.hadess.PowerProfiles API used by older PPD versions and compatible implementations such as tuned-ppd.
• Preserve direct platform_profile handling when neither API exists, desiredprof cannot be represented by a PPD hold, or defaultprof requests exact restoration semantics.
• Do not bypass a present policy daemon after authorization or operational errors.
• Let PPD restore the user-selected base profile when the hold ends.

No new dependency or configuration option is added; the implementation uses the existing sd-bus dependency.

Testing

• scripts/format-check.sh
• Meson build with -Dwith-examples=true
• meson test -C builddir --print-errorlogs
• Live PPD 0.30 modern endpoint: hold appears with the expected application ID, profile, and reason, then disappears on release
• Two concurrent clients: one hold remains until the final client exits
• Forced GameMode daemon exit: D-Bus disconnect removes the hold
• clang-tidy on the changed daemon sources (only existing project-wide logging warnings)

Full gamemoded -t hardware validation is pending the local removal of competing ASUS profile writers, hence this is submitted as a draft.

Fixes #333
Fixes #462