Embed an Orleans silo in the Uno desktop host and register the core grains

[KSemenenko]

Problem

The desktop app needs an embedded Orleans host so dotPilot can manage durable local-first session state.

Scope

• Host Orleans inside the Uno desktop startup path
• Register the initial Session, Workspace, Fleet, Policy, and Artifact grains
• Define startup and shutdown expectations for the embedded host

Out of scope

• Remote silo hosting
• UI composition details outside host lifecycle requirements

Implementation notes

• Keep the first host cut local-first and desktop-embedded
• Ensure later provider and orchestration work has stable grain entry points
• Align with the ADR and architecture map

Definition of Done

• The issue defines the embedded host responsibilities and the initial grain list
• Startup, shutdown, and local-state expectations are explicit

Verification

• Future Orleans implementation can proceed without re-deciding the host shape

Dependencies

• Parent epic: [Epic] Add the embedded agent runtime host to the Uno desktop app #12
• Depends on: [Epic] Establish dotPilot as a desktop control plane for local-first agent operations #11