feat: Allow configuration of espnow_main task core affinity, priority, and stack size (AEGHB-1152)

[finger563]

Description

This allows callers to provide configuration for the espnow_main task, configuring the stack size, priority, and core id if desired. The default parameters are set to maintain the same behavior as today.

Related

Closes #147

Testing

I've locally built the get-started example within this repository to ensure that it properly builds without warnings against ESP-IDF v5.4.1

Checklist

Before submitting a Pull Request, please ensure the following:

• 🚨 This PR does not introduce breaking changes.
• All CI checks (GH Actions) pass.
• Documentation is updated as needed.
• Tests are updated or added as necessary.
• Code is well-commented, especially in complex areas.
• Git history is clean — commits are squashed to the minimum necessary.