Define the dotPilot domain model for agents, sessions, fleets, tools, artifacts, and evaluations #22

Problem

Implementation work needs stable contracts before runtime or UI features can land without churn.

Scope

• Introduce typed identifiers such as WorkspaceId, AgentProfileId, SessionId, FleetId, ProviderId, and ModelRuntimeId
• Define session phase, connection status, approval, artifact, telemetry, and evaluation records
• Capture the model relationships in docs and issue references

Out of scope

• Concrete runtime implementation of the contracts
• UI polish for displaying the contracts

Implementation notes

• Use the approved ADR and feature spec as the source of truth
• Keep contracts broad enough for coding and non-coding agents
• Prefer versionable DTOs and serialization-safe record shapes

Definition of Done

• The planned contract set is documented and tracked
• The issue defines the minimum contract surface needed before implementation begins
• Future adapter, runtime, and UI issues can reference these contracts directly

Verification

• Spot-check child issues in later epics to confirm they can reference this issue cleanly

Dependencies

• Parent epic: [Epic] Establish dotPilot as a desktop control plane for local-first agent operations #11
• Related docs: docs/ADR/ADR-0001-agent-control-plane-architecture.md, docs/Features/agent-control-plane-experience.md