[Plan-14] Increment 5: Session log integration

[basmeerman]

Context

Plan 14: CircuitMeter — Increment 5 of 6

Scope

Add circuit energy fields to session_record_t for ERE reporting.

Acceptance Criteria

• session_record_t has circuit_start_energy_wh, circuit_end_energy_wh, circuit_energy_wh
• session_start extended to accept circuit start energy
• JSON output includes circuit_kwh when > 0
• Backwards compatible: circuit fields default to 0 when CircuitMeter disabled
• Existing session tests still pass

Dependencies

Increment 4

Files

• Modify: src/session_log.h, src/session_log.c, test/native/tests/test_session_log.c

[basmeerman]

Implemented in PR #117 (merged to master).