D-Bus Phase 3/4: upgrade sessiond, services, add StatusNotifierWatcher, consolidate configs

- redbear-sessiond: add Manager.Inhibit (pipe FD), CanPowerOff/CanReboot/
  CanSuspend/CanHibernate/CanHybridSleep/CanSleep (return na), PowerOff/
  Reboot/Suspend stubs, GetSessionByPID, ListUsers, ListSeats,
  ListInhibitors, ActivateSession/LockSession/UnlockSession/TerminateSession
- redbear-sessiond: add Session SetIdleHint, SetLockedHint, SetType,
  Terminate methods; wire PauseDevice/ResumeDevice/Lock/Unlock signal
  emission via SignalEmitter injection; add dynamic device enumeration
  scanning /scheme/drm/card* and /dev/input/event* at startup
- redbear-sessiond: replace infinite pending() with stoppable shutdown
  via tokio watch channel + control socket shutdown command
- redbear-upower: add Changed signal emission with 30s periodic polling
  and power state snapshot comparison
- redbear-notifications: add ActionInvoked signal, expand capabilities
  to body + body-markup + actions
- redbear-polkit, redbear-udisks: replace pending() with stoppable
  shutdown via signal handling + watch channel
- Add redbear-statusnotifierwatcher: new session bus service implementing
  org.freedesktop.StatusNotifierWatcher for KDE system tray
- Add D-Bus activation file for StatusNotifierWatcher
- KWin session.cpp: try LogindSession before NoopSession fallback
- Consolidate config profiles: remove obsolete redbear-desktop, redbear-kde,
  redbear-live-*, redbear-minimal-*, redbear-wayland configs; simplify
  to three supported targets (redbear-full, redbear-mini, redbear-grub)
- Update DBUS-INTEGRATION-PLAN.md and DESKTOP-STACK-CURRENT-STATUS.md
  with Phase 3/4 fragility assessment, KWin readiness matrix, and
  completeness gap analysis

local/docs/ACPI-I2C-HID-IMPLEMENTATION-PLAN.md

@@ -56,7 +56,7 @@ This work must be treated as bare-metal boot-critical substrate, not as optional
   Emits RB_THC_QUICKI2C, RB_UCSI_* markers. Consumes `/scheme/ucsi/summary`.
 - **`amlserde`** — AML serialization/deserialization, including `AmlSerdeValue::Buffer`
   (needed for `_CRS`), `RegionSpace::GenericSerialBus` for I2C/SMBus opregions.
-- **Init services** — `redbear-live-mini.toml` wires `i2cd`, `i2c-hidd`, `i2c-dw-acpi`,
+- **Init services** — `redbear-mini.toml` wires `i2cd`, `i2c-hidd`, `i2c-dw-acpi`,
   `i2c-gpio-expanderd`, `intel-gpiod`, `ucsid` with non-blocking startup ordering.
 
 ### What is missing (active gaps)