fix: KeyError on first skills_tool:load call

[QuantFoundry]

Problem

skills_tool._load() raises KeyError: 'loaded_skills' on the first call in any session because agent.data is a plain dict and the key has not been initialized yet.

# This line throws KeyError on first call:
if not self.agent.data[DATA_NAME_LOADED_SKILLS]:

The except block in execute() catches the exception and returns it to the agent as:

Error in skills_tool: 'loaded_skills'

This silently breaks every skills_tool:load call in a fresh session. The agent receives an error, cannot load the skill, and falls back to guessing or reading files manually.

Fix

Use .get() instead of direct dict access — returns None (falsy) when the key does not exist, allowing the initialization on the next line to proceed normally.

- if not self.agent.data[DATA_NAME_LOADED_SKILLS]:
+ if not self.agent.data.get(DATA_NAME_LOADED_SKILLS):

Testing

Verified in a live Agent Zero session: skills_tool:load now succeeds on the first call with no errors.