v3.2.0-beta.1 — charge-interval capture (BETA)

Beta for testers, before the official 3.2 deploy. Adds real charge-interval capture: the gateway records each actual charge burst (cp>0) — when charging really happened, not plug-in time — via /api/charge_log + status summary + 2 new MQTT entities (Last Charge Burst, Recorded Charge Bursts) + per-interval solar split. Builds on the 3.2 charge-reminder + control-owner work. OTA the attached firmware.bin (MD5 5be35b855062e817ea83183fee6594a3). Pre-release — not the stable channel.