feat: outbound voice call essentials (#12782)

- Enables outbound voice calls in voice channel . We are only caring
about wiring the logic to trigger outgoing calls to the call button
introduced in previous PRs. We will connect it to call component in
subsequent PRs

ref: #11602 

## Screens

<img width="2304" height="1202" alt="image"
src="https://github.com/user-attachments/assets/b91543a8-8d4e-4229-bd80-9727b42c7b0f"
/>

<img width="2304" height="1200" alt="image"
src="https://github.com/user-attachments/assets/1a1dad2a-8cb2-4aa2-9702-c062416556a7"
/>

---------

Co-authored-by: Sivin Varghese <64252451+iamsivin@users.noreply.github.com>
Co-authored-by: iamsivin <iamsivin@gmail.com>
Co-authored-by: Vishnu Narayanan <vishnu@chatwoot.com>

AGENTS.md

@@ -10,6 +10,9 @@
 - **Test Ruby**: `bundle exec rspec spec/path/to/file_spec.rb`
 - **Single Test**: `bundle exec rspec spec/path/to/file_spec.rb:LINE_NUMBER`
 - **Run Project**: `overmind start -f Procfile.dev`
+- **Ruby Version**: Manage Ruby via `rbenv` and install the version listed in `.ruby-version` (e.g., `rbenv install $(cat .ruby-version)`)
+- **rbenv setup**: Before running any `bundle` or `rspec` commands, init rbenv in your shell (`eval "$(rbenv init -)"`) so the correct Ruby/Bundler versions are used
+- Always prefer `bundle exec` for Ruby CLI tasks (rspec, rake, rubocop, etc.)
 
 ## Code Style
 
@@ -37,6 +40,8 @@
 
 - MVP focus: Least code change, happy-path only
 - No unnecessary defensive programming
+- Ship the happy path first: limit guards/fallbacks to what production has proven necessary, then iterate
+- Prefer minimal, readable code over elaborate abstractions; clarity beats cleverness
 - Break down complex tasks into small, testable units
 - Iterate after confirmation
 - Avoid writing specs unless explicitly asked