Clarify nexus workflow ID naming

[Sushisource]

Summary

• rename Nexus starter workflow IDs to include caller context and avoid abbreviations while keeping timestamp uniqueness
• update context propagation handler workflow ID to use full sample naming instead of abbreviations
• restore Nexus caller samples to use the original Spanish language argument

Testing

• go test ./nexus-context-propagation/... ./nexus-multiple-arguments/... (fails: proxy.golang.org access forbidden)

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Codex Task