Add support for AMR eMUCS-A1 – V5.0.1 DSMR messages

**Describe the problem you have/What new integration you would like**

The A1 port of the industrial meter has the same physical interface as the P1 port of the residential meter, but the telegrams are different. Request to support these telegrams side by side.

**Please describe your use case for this integration and alternatives you've tried:**

Readout DSMR values in common with the P1 standard, but also include the values specifically related to the A1 standard. Handle the differences in the parser.

**Additional context**

Specification:
[AMR eMUCS-A1_E.5.0-1.pdf](https://github.com/user-attachments/files/18183946/AMR.eMUCS-A1_E.5.0-1.pdf)

Start by reading the linked AMR eMUCS-A1_E.5.0-1 specification and locating the existing DSMR/P1 telegram parser in the implementation repository. Compare the A1 telegram fields with the current P1 handling; done means both formats are accepted, common DSMR values remain available, and A1-specific values are included.

Written by the indexing model from the issue text.