Replace MQTT output with direct InfluxDB writes

Polls now cover meter 1, battery 1 and storage control blocks,
plus inverter event registers for off-grid detection (vendor
event bit 0). Register layout validated by probing a
SE10K-RWB48BFN4 with fw 0004.0025.0011; battery and storage
floats are word-swapped on this device.

Failed Influx writes spool to disk and replay on the next
success (Influx reached over WAN). Modbus blocks that fail to
read are skipped for that cycle; the flaky gateway must not
kill the daemon. Battery lifetime counters at 0xE176/0xE17A
hang the device and are never read.

BREAKING CHANGE: config.yaml 'mqtt:' section replaced by
'influx:', Home Assistant discovery removed.

requirements.txt

@@ -1,3 +1,2 @@
-paho-mqtt>=1.5.0
-solaredge_modbus>=0.2.0
-pyyaml>=5.3
+pymodbus>=2.0,<3.0
+pyyaml>=5.3