fix(display): redesign module layout - integer minutes, dedicated error slots
New module assignment:
Module 0 : WiFi error indicator (showWifiError) - 'W' / blank
Module 1-3 : laser time in full minutes, 3-digit right-aligned
Module 4 : MQTT error indicator (showMqttError) - 'M' / blank
Module 5-7 : countdown seconds / idle / status, 3-digit right-aligned
Changes in display_manager.h:
- Update zone layout comments
- showLaserTime: integer minutes only, writes modules 1-3 (module 0 untouched)
- showCountdown: writes modules 5-7 only (module 4 untouched)
- showIdle: ' --' on modules 5-7
- showStatus: 3-char string on modules 5-7
- Add showWifiError(bool): module 0
- Add showMqttError(bool): module 4
Changes in display_manager.cpp:
- Add BMP_M character bitmap
- Add 'M' case in charBitmap()
- Rewrite showLaserTime() - round to int, 3 chars, modules 1-3
- Rewrite showCountdown() - 3 chars, modules 5-7
- Rewrite showIdle() - ' --' on modules 5-7
- Rewrite showStatus() - 3 chars, modules 5-7
- Add showWifiError() / showMqttError() implementations
- Update printToSerial() log output
Changes in test_sketch:
- 9 test steps covering all new methods incl. combination test
- Tested on hardware: all steps passed
26a4e9b95c
