[EL15] Improve BLE write reliability, CAP setpoint handling, and status decoding

[maj113]

Summary

This PR improves the EL15 BLE integration in a few focused areas:

• serialize EL15 writes so set/mode actions do not race against polling
• add proper CAP-mode setpoint handling using the CAP-specific write/readback path
• treat CAP setpoints as integer mA values in the UI and protocol bridge
• improve fault and cycle-end handling, including clear support and short status codes
• show timer status when the timer flag is active during load-on
• fix DCR mode so the main readings show actual current and computed power, while DCR-specific values remain in the detail field

Details

Write reliability

EL15 writes now wait for the device notification path instead of racing a poll request. This fixes cases where setpoint or mode changes were unreliable.

CAP mode

CAP mode now uses its dedicated BLE command flow instead of the normal setpoint path:

• CAP set uses the CAP-specific write opcode
• CAP readback uses the CAP-specific read opcode
• the UI displays CAP setpoint in whole mA
• CAP values are quantized/clamped to the supported integer mA range

Fault and cycle handling

Fault decoding is more explicit now:

• cycle/timer end / alarm clear goes through the proper packed control command
• load and lock controls both use the packed control path correctly

Runtime / timer display

When the EL15 timer flag is set and load is on, the runtime field is shown as Timer ... instead of Runtime ....

DCR mode

DCR packets carry a real current field that can be used to compute power. The UI now shows:

• main readings: voltage / current / computed power
• detail field: I1 / I2 / R