feat(cli): spacesh restart --resume flag (plan gap: CLI is a first-class client)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/spacesh-cli/src/cli.rs

@@ -38,7 +38,11 @@ pub enum Sub {
     },
     Close { surface_id: String },
     Focus { surface_id: String },
-    Restart { surface_id: String },
+    Restart {
+        surface_id: String,
+        /// Relaunch the agent with its session-continue flag (e.g. claude --continue).
+        #[arg(long)] resume: bool,
+    },
     Notify {
         #[arg(long)] surface: String,
         #[arg(long, value_enum)] state: StateArg,

crates/spacesh-cli/src/mapping.rs

@@ -29,7 +29,7 @@ pub fn to_cmd(sub: Sub) -> Cmd {
         },
         Sub::Close { surface_id } => Cmd::Close { surface_id: SurfaceId(surface_id) },
         Sub::Focus { surface_id } => Cmd::Focus { surface_id: SurfaceId(surface_id) },
-        Sub::Restart { surface_id } => Cmd::RestartSurface { surface_id: SurfaceId(surface_id) },
+        Sub::Restart { surface_id, resume } => Cmd::RestartSurface { surface_id: SurfaceId(surface_id), resume },
         Sub::Notify { surface, state } => Cmd::SetState { surface_id: SurfaceId(surface), state: state_of(state) },
         Sub::ApplyPreset { workspace_id, preset, agents } => Cmd::ApplyPreset {
             workspace_id: WorkspaceId(workspace_id),