Add SDT4E425 dual-sensor streams and RPC2 PTZ presets

[Realcrash]

Summary

Adds model-specific support for the Dahua SDT4E425 dual-sensor PTZ camera family.

• Detects DH-SDT4E425-4F-GB-A-PV1 and compatible model strings.
• Exposes three streams for each physical sensor:
  • Panorama Main, Sub and Sub_2
  • PTZ Main, Sub and Sub_2
• Maps Panorama to RTSP channel 1 and PTZ to RTSP channel 2.
• Uses the camera's RPC2 Web 5.0 flow for PTZ preset enumeration and GotoPreset.
• Avoids the unsupported CGI ptz.cgi?action=getStatus request for this model.
• Keeps the existing behavior unchanged for other Dahua models.

Hardware validation

Tested on:

DH-SDT4E425-4F-GB-A-PV1

Validated stream matrix:

Entity	RTSP mapping
Panorama	channel=1&subtype=0
Panorama Sub	channel=1&subtype=1
Panorama Sub_2	channel=1&subtype=2
PTZ	channel=2&subtype=0
PTZ Sub	channel=2&subtype=1
PTZ Sub_2	channel=2&subtype=2

All six streams were visually verified when the corresponding encoder profiles were enabled on the camera.

The camera returns the expected RTSP 404 response when a Sub or Sub_2 encoder profile is disabled. The entity remains present because the integration exposes the device's declared stream slots.

PTZ validation:

• 5 configured presets were enumerated dynamically.
• GotoPreset was successfully tested for the available presets.
• RPC2 login, factory instance creation and logout completed successfully.
• No invalid-session errors were observed.
• Normal logging remains quiet; detailed RPC2 messages are DEBUG-only.

Tests

Adds tests covering:

• SDT4E425 model matching
• RPC2 login and PTZ preset payloads
• six camera entities with distinct channel/subtype mappings
• preservation of behavior for other models

Fixes #589