Add state_class to Growatt power and energy sensors

[johanzander]

Proposed change

Fixes power and energy sensors not appearing in Energy dashboard by adding missing state_class attributes:

• Power sensors: Added state_class=MEASUREMENT for instantaneous power readings
• Energy sensors (daily): Added state_class=TOTAL_INCREASING for daily counters that reset
• Energy sensors (lifetime): Already had state_class=TOTAL (no changes needed)

Affected files:

• mix.py: 9 power sensors, 9 energy sensors
• tlx.py: 15 power sensors
• total.py: 1 power sensor

This resolves the issue where "Load Consumption" and other power sensors were not selectable in the Home Assistant Energy dashboard configuration.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: Growatt integration load consumption incorrect class for Power dashboard #158692 (comment)

Checklist

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