Add /compact Command

Solves -> #421

Adds a new /compact command that allows users to manually trigger conversation context summarization to reduce token usage.

Changes

• Added event constant and handler for compact command
• Updated software-engineer agent to subscribe to compact events
• Added compact command to default workflow configuration
• Updated documentation to include the new command

Testing

Verified that the command properly triggers context compaction and reduces token usage.

/claim #421