shared protobuf definitions for the sunbeam code agent:
- CodeAgent service with bidirectional Session streaming
- ClientMessage: StartSession, UserInput, ToolResult, ToolApproval
- ServerMessage: TextDelta, ToolCall, ApprovalNeeded, Status
- ToolDef for client-side tool registration
this is the transport layer between `sunbeam code` (TUI client)
and Sol (server-side agent loop). next: JWT middleware for OIDC
auth, Sol gRPC server stub, CLI subcommand stub.
Sienna Meridian Satterwhite
f3e67e589b
