.NET Aspire orchestration and OpenTelemetry setup

[mikemcdougall]

Summary

Configure .NET Aspire for local development with OpenTelemetry observability foundation.

Tasks

• Create Honua.AppHost project with PostgreSQL/PostGIS container
• Create Honua.ServiceDefaults with shared OpenTelemetry config
• Configure traces (ASP.NET Core, HttpClient, Npgsql)
• Configure metrics (ASP.NET Core, runtime, custom Honua meters)
• Configure OTLP export when OTEL_EXPORTER_OTLP_ENDPOINT is set
• Add optional Redis container for caching

Reference

See MVP_PLAN.md ".NET Aspire" section for configuration patterns.

Acceptance Criteria

• Single dotnet run starts Honua + PostgreSQL via Aspire
• Aspire dashboard shows traces, logs, metrics
• OpenTelemetry exports to OTLP collector when configured
• No Aspire runtime dependencies in published container