v0.1.0-dev.2.25

observability

• Add root-level observability package with OTel-aligned severity levels (#25)
• Add Observer interface, Event struct, and Level type with OTel SeverityNumber values (#25)
• Add SlogObserver with level-aware log emission and flattened attributes (#25)
• Add NoOpObserver, MultiObserver, and global observer registry (#25)

orchestrate

• Migrate orchestrate/observability to root-level observability package (#25)
• Add Level field to all event emissions with Info/Verbose/Warning assignments (#25)
• Add node.state event type separating state snapshots from node.complete (#25)
• Decentralize event type constants into orchestrate/state/events.go and orchestrate/workflows/events.go (#25)

kernel

• Replace *slog.Logger with observability.Observer in kernel runtime loop (#25)
• Add WithObserver option replacing WithLogger (#25)
• Add kernel event type constants: run, iteration, tool call, response, error (#25)
• Default to SlogObserver(slog.Default()) for out-of-the-box observability (#25)