team-operator: Add OpenTelemetry tracing

[ian-flores]

Summary

Add OTel traces for Reconcile calls, with operator-rooted spans, optional inbound trace context propagation via annotation, and outbound trace IDs surfaced in CR status.

Acceptance Criteria

• One root span per Reconcile; Site reconciler emits child spans for each sub-dispatcher
• .status.observability.lastTraceID populated on errors and meaningful changes
• Optional posit.co/traceparent annotation parsed as an OTel Link if present
• Default off (--observability-traces-enabled=false); flag flip enables
• Active span's trace_id injected into existing zap log fields

Design: #7 (comment) (Phase 3 section)

Phase 3 of three. Phase 1: #7. Phase 2: #132.