Fix 3-phase AC sensors showing zero/unknown on MOD and SPH TL3

[0xAHA]

PROBLEM:
User reported 3-phase AC voltage, current, and power sensors showing as "unknown" or not appearing at all on MOD 6000-15000TL3-XH inverter. Register scan showed valid AC data but sensors weren't created.

ROOT CAUSES:

1. Register name mismatch:

   • Profiles defined: 'ac_voltage_r', 'ac_current_r', 'ac_power_r_low'
   • Code looked for: 'ac_voltage', 'ac_current', 'ac_power_low'
   • Result: Registers not found → zero values

2. Missing dataclass fields:

   • GrowattData only had generic ac_voltage/current/power
   • No individual phase fields (ac_voltage_r/s/t, etc.)

3. Missing sensors from profile:

   • THREE_PHASE_SENSORS didn't include 'ac_voltage_r/s/t'
   • Sensors defined but not enabled

4. No code to read individual phases:

   • Only generic AC reading code existed
   • Individual 3-phase registers never accessed

FIXES:

1. Enhanced register lookup to support aliases:

   • _find_register_by_name() now checks both 'name' and 'alias'
   • Allows phase-specific registers to be found by generic names

2. Added generic aliases in profiles (MOD and SPH TL3):

   • ac_voltage_r → alias 'ac_voltage'
   • ac_current_r → alias 'ac_current'
   • ac_power_r_low → alias 'ac_power_low'
   • Phase R serves as "main" AC output for compatibility

3. Added 3-phase fields to GrowattData dataclass:

   • ac_voltage_r/s/t, ac_current_r/s/t, ac_power_r/s/t
   • ac_voltage_rs/st/tr (line-to-line)

4. Added code to read individual 3-phase registers:

   • Reads all phases R, S, T individually
   • Reads line-to-line voltages
   • Populates all phase-specific dataclass fields

5. Updated THREE_PHASE_SENSORS:

   • Added 'ac_voltage_r', 'ac_voltage_s', 'ac_voltage_t'
   • Now all phase sensors are enabled

RESULT:

• Generic AC sensors (ac_voltage/current/power) now work via Phase R alias
• Individual phase sensors (R/S/T) now populate with correct values
• All 3-phase inverters (MOD, SPH TL3) get full 3-phase monitoring
• Backwards compatible with existing configs