ESP32 Firmware Build .40

Improve ePaper longevity, display reliability, and fetch retry coverage

Display power:
- Replace powerOff() with hibernate() for AP config and demo screens to
  properly park the controller before power-off
- For the main sleep cycle, use hibernate() only before a scheduled full
  refresh; use powerOff() otherwise so the controller's partial-refresh
  frame buffer stays intact (fixes corrupted display on second boot)

Fetch retry:
- fetchBambu and fetchProxmoxStates now return bool; failures set
  pendingBambuRetry / pendingProxmoxRetry in RTC memory so the next
  wake retries immediately regardless of the normal refresh schedule
- WiFi failure branch now sets Proxmox and Bambu retry flags when those
  fetches were due, not just the Google Script path

SuperMini LED feedback:
- Add updateSuperMiniHoldFeedback(): green -> cyan flash -> white flash as
  button hold crosses demo then config thresholds
- Flash green on demo release, red on config-mode release

Status bar layout:
- iconReserve is now conditional on battery pin presence and zigbee_enable
  so the version string is not pushed off-screen on boards without those
- forceUpdateStatusBar set after Bambu fetch to keep printer icon current

AMS tray display (bambulab):
- Cleaner tray state logic using a local Tray& reference; show % when
  remain >= 0, -- when type known but no remain, EMPTY otherwise