NethVoice: add ASR and summarization features backend

[Amygos]

Proposed Feature
Implement backend features for NethVoice to support:

• Automatic Speech Recognition (ASR) for audio files, including voicemail transcription for notification emails
• ASR for audio streaming, enabling real-time call transcription
• Text summarization for processing and summarizing phone call transcripts

Purpose and Motivation
The purpose of these features is to enhance NethVoice with advanced AI-driven tools that improve user efficiency and accessibility. Voicemail transcription will allow users to quickly read message content in notifications, while real-time call transcription supports compliance, documentation, and accessibility. Text summarization of transcripts provides concise insights and easier management of communication records.

Additional Context
This request focuses solely on backend implementation; frontend adaptations are out of scope.

[Amygos]

Test case:

Voicemail transcription

• Enable voicemail transcription on NethVoice NS8 settings interface
• Add a Deepgram API key on NethVoice NS8 settings interface
• Configure email notification on NS8 admin interface: Settings --> Email notifications
• Enable voicemail for a user, from NethVoice's Wizard: Configurations --> Users
• From NethVoice's Wizard, go to FreePBX Administration interface, Admin --> Advanced :
  • Edit the user's extension settings. Applications --> Extensions:
    • Add an email address for the user's voicemail,Voicemail --> Email Address
    • Enable voicemail attachment, Voicemail --> Email Attachment
• Make a call and leave a message

Realtime call transcription

• From shell access, set a Deepgram API key and OpenAI API key on NethVoice NS8 environment, and enable realtime call transcription and final call summarization, eg:

runagent -m nethvoice1 sed -ie 's/\(OPENAI_API_KEY\)=.*/\1=<<OPENAI_KEY>>/'  passwords.env
runagent -m nethvoice1 sed -ie 's/\(DEEPGRAM_API_KEY\)=.*/\1=<<DEEPGRAM_KEY>>/'  passwords.env
runagent -m nethvoice1 sed -ie 's/\(SATELLITE_CALL_TRANSCRIPTION_ENABLED\)=False/\1=True/' environment

• restart the relevant services:

runagent -m nethvoice1 systemctl --user restart satellite satellite-mqtt freepbx

• subscribe satellite/* MQTT topics on satellite-mqtt broker

runagent -m nethvoice1 podman exec --env-file environment  --env-file passwords.env -it satellite-mqtt sh -c 'mosquitto_sub -h 127.0.0.1 -p $SATELLITE_MQTT_PORT -u $SATELLITE_MQTT_USERNAME -P $SATELLITE_MQTT_PASSWORD -t "#" -v'

• make inbound and outbound calls

Originally posted by @Stell0 in #7248

[Amygos]

Testing release nethesis/ns8-nethvoice 1.4.3-testing.12