feat: add dict-like .get() method to AgentConfig dataclass

[gdeyoung]

Summary

Adds a .get(key, default) method to the AgentConfig dataclass to provide dict-like access to config attributes.

Problem

AgentConfig is a @DataClass used throughout the framework as a configuration object. Extensions, skills, and external tools often receive config objects and expect dict-like .get() access with default values.

Without this method, code that calls config.get('key', default) raises:

AttributeError: 'AgentConfig' object has no attribute 'get'

This caused 7 scheduled jobs in our deployment to fail silently.

Solution

Adds a .get() method that:

• Returns the dataclass attribute if it exists
• Falls back to the additional dict for extra config values
• Returns the provided default if key is not found

Changes

• agent.py: Added get() method to AgentConfig class (lines 317-335)

Backwards Compatibility

Fully backwards compatible. No existing behavior changes. Only adds a new method.

Testing

• Verified the method returns correct values for existing attributes
• Verified fallback to additional dict works
• Verified default value is returned for unknown keys
• 7 previously failing scheduled jobs now run successfully

[gdeyoung]

Closing this PR to resubmit cleanly from a synced fork (v1.7). The fork was 578 commits behind upstream. Will resubmit with a fresh branch.