fix: JSON output for workflow update execute/result commands

[wucm667]

Problem

When using -o json with temporal workflow update execute or temporal workflow update result:

1. Update failure returns no JSON — errors are returned as plain fmt.Errorf, breaking JSON output mode. Users expect structured JSON even on failure.

2. --no-json-shorthand-payloads flag is silently ignored — update results always decode payloads with the default converter, regardless of the flag. This differs from other commands like activity complete which properly respect this option.

Root Cause

Located in workflowUpdateHelper (internal/temporalcli/commands.workflow.go):

• Line ~488: Update failure returns fmt.Errorf("unable to update workflow: %w", err), which bypasses the JSON printer entirely.
• Lines ~491-497: Result is printed as interface{} without checking cctx.JSONShorthandPayloads, ignoring the --no-json-shorthand-payloads flag.

Fix

1. JSON error output: When cctx.JSONOutput is true and the update fails, use cctx.Printer.PrintStructured to return a structured JSON response with name, updateId, and error fields. Falls back to the existing fmt.Errorf for non-JSON mode.

2. Respect --no-json-shorthand-payloads: Added conditional serialization based on cctx.JSONShorthandPayloads:

   • true (default): decode payloads via converter.GetDefaultDataConverter().FromPayloads() for clean JSON output
   • false: use cctx.MarshalProtoJSON() for raw protobuf JSON representation

This matches the pattern used in printActivityResult (commands.activity.go line 282).

Testing

• Existing TestWorkflow_Update_Execute and TestWorkflow_Update_Result tests pass.
• Build compiles cleanly with go build ./internal/temporalcli/....

Fixes #952

[CLAassistant]

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