Add tariff counter support (Tariff 1 & 2) for import/export

[matlab22]

Adds support for separate tariff-based accumulated energy counters (Tariff 1 and Tariff 2) for both active import and export. Enables detailed tracking of energy consumption across different rate periods.

Fixes: Landis+Gyr parser bug where tariff values were read from meter but not stored.

Changes

Core Data Model

• AmsData.h/cpp: Added activeImportCounterTariff1/2 and activeExportCounterTariff1/2 fields with getters
• Modified apply() methods to handle OBIS tariff values (gr=8, tariff=1/2) and copy tariff counters between instances

Meter Parsers

• IEC6205675.h/cpp: Added OBIS constants and parsing for 1.8.1, 1.8.2, 2.8.1, 2.8.2 (Iskra meters)
• LNG.cpp: Fixed bug - parser now stores tariff values (o181, o182, o281, o282) instead of only summing them

MQTT Integration

• JsonMqttHandler.cpp: Added tPIT1, tPIT2, tPOT1, tPOT2 fields to list3/list4 JSON
• RawMqttHandler.cpp: Added topics for /meter/import/export/active/accumulated/tariff1 and /tariff2

Web UI

• data.json: Added ict1, ict2, ect1, ect2 fields to data API
• AmsWebServer.cpp: Populated tariff counter values in JSON response
• Dashboard.svelte: Display tariff breakdown below total counters (only when tariff data present)

Compatibility

• Fully backward compatible
• Existing integrations continue with total counters (tPI, tPO)
• Tariff fields only display when meter provides non-zero values

Testing

• Tested on ESP32-C3 with Landis+Gyr meter
• Verified MQTT JSON/Raw outputs
• Confirmed UI displays tariff breakdown
• Validated DLMS/HDLC parsing