Add platformId to agent details for cross-platform observability

[Copilot]

Add optional platformId property to agent details and telemetry

[Copilot]

Pull request overview

This PR adds optional platformId support to agent details and telemetry infrastructure for cross-platform observability. The changes enable tracking of platform identifiers for both agents and caller agents across the telemetry stack.

• Adds platformId property to AgentDetails and EnhancedAgentDetails interfaces
• Integrates platformId into OpenTelemetry span attributes and baggage propagation
• Provides comprehensive test coverage for the new functionality

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
packages/agents-a365-observability/src/tracing/constants.ts	Adds two new OpenTelemetry constants for agent and caller agent platform IDs
packages/agents-a365-observability/src/tracing/contracts.ts	Adds optional platformId property to AgentDetails and EnhancedAgentDetails interfaces
packages/agents-a365-observability/src/tracing/scopes/OpenTelemetryScope.ts	Sets platform ID tag when creating spans with agent details
packages/agents-a365-observability/src/tracing/scopes/InvokeAgentScope.ts	Propagates caller agent platform ID in span attributes
packages/agents-a365-observability/src/tracing/middleware/BaggageBuilder.ts	Adds fluent API methods for setting agent and caller agent platform IDs in baggage
packages/agents-a365-observability/src/tracing/processors/util.ts	Includes platform ID constants in generic and invoke agent attribute arrays
tests/observability/core/scopes.test.ts	Adds test cases verifying platform ID creation and propagation in scopes
tests/observability/core/BaggageBuilder.test.ts	Adds test cases for platform ID baggage builder methods

OOF and comment is addressed.