Add canonical activity_log.csv schema for agent tracking

Establishes canonical CSV schema for activity tracking with standardized columns:
- timestamp: ISO 8601 format (UTC)
- agent_id: identifier for the agent performing the activity
- activity_type: type of activity (init, read, write, update, delete, query, etc.)
- entity_id: identifier for the entity being acted upon
- status: status of the activity (created, updated, success, failed, pending, etc.)
- notes: human-readable description of the activity
- context: additional context or metadata about the activity

This schema provides a clean foundation for agent integration and data flow tracking.

activity_log.csv

@@ -0,0 +1,2 @@
+timestamp,agent_id,activity_type,entity_id,status,notes,context
+2025-11-05T10:51:00Z,comet_assistant,init,activity_log_schema,created,"Canonical CSV schema for activity tracking established","Step 1: Schema and CSV Foundation - initial setup"