feat: scaffold codespace backend

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

internal/process/session.go

@@ -0,0 +1,17 @@
+package process
+
+import "os/exec"
+
+// Status represents the status of a process for a workspace.
+type Status struct {
+	WorkspaceID string `json:"workspaceId"`
+	Running     bool   `json:"running"`
+	PID         int    `json:"pid,omitempty"`
+}
+
+// Session holds the runtime state of a started OpenCode process.
+type Session struct {
+	WorkspaceID string
+	Root        string
+	Cmd         *exec.Cmd
+}