fix: SSH actions in experiment runner, branch ID serialization, and branch UI

- robot-communication.ts: add sshCommand to payloadMapping type
- trial-execution.ts: fix executeRobotActionWithComm to use ros2 key as
  implementation fallback and skip ROS connection for SSH actions
- route.ts: move studyId membership check inside initialize/executeSystemAction
  cases so executeSSH works without studyId; fix command param location
- experiments.ts: build tempId→dbUUID map on step insert and replace branch
  nextStepId references after all steps are saved
- WizardInterface.tsx: stop filtering branch actions from step action list

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/server/services/robot-communication.ts

@@ -30,6 +30,7 @@ export interface RobotAction {
       type?: string;
       transformFn?: string;
       payload?: Record<string, unknown>;
+      sshCommand?: string;
     };
     ros2?: {
       topic?: string;
@@ -40,6 +41,7 @@ export interface RobotAction {
         type?: string;
         transformFn?: string;
         payload?: Record<string, unknown>;
+        sshCommand?: string;
       };
     };
   };