[docs] Enhance Azure Functions and package architecture documentation

- Add NuGet package architecture section explaining Datadog.Trace vs Datadog.AzureFunctions packages
- Document ASP.NET Core integration, HTTP proxying, and trace context propagation
- Add comprehensive troubleshooting guide for Azure Functions with log analysis workflows
- Include distributed tracing architecture explanation with host/worker process span handling
- Add new QueryingDatadogAPIs.md guide for debugging with Datadog APIs
- Update AGENTS.md with package references

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: lucaspimentel

AGENTS.md

@@ -19,6 +19,25 @@
 - Loader/home: Build outputs publish a "monitoring home"; the native loader boots the tracer from there.
 - Build system: Nuke coordinates .NET builds and CMake/vcpkg for native components.
 
+## NuGet Package Architecture
+
+### Datadog.Trace Package
+The `Datadog.Trace` NuGet package provides the **manual instrumentation API** for customers:
+- **Contains**: `Datadog.Trace.Manual.dll` - Public API for manual instrumentation
+- **Does NOT contain**: Auto-instrumentation code or native profiler binaries
+- **Usage**: Reference in application code for manual tracing (e.g., `Tracer.Instance.StartActive()`)
+
+Auto-instrumentation comes from the tracer "monitoring home" deployed separately (via installers, MSI, container images, or specialized packages like `Datadog.AzureFunctions`).
+
+### Datadog.Trace.dll vs Datadog.Trace.Manual.dll
+- `Datadog.Trace.dll` - The full managed tracer with all auto-instrumentation code, loaded by the native profiler into instrumented processes
+- `Datadog.Trace.Manual.dll` - Lightweight manual instrumentation API packaged in the `Datadog.Trace` NuGet package for customer reference
+
+### Specialized Packages
+- **Datadog.AzureFunctions**: Bundles `Datadog.Trace.dll` and native profiler for Azure Functions (see `docs/development/AzureFunctions.md`)
+- **Datadog.Monitoring.Distribution**: MSI installer for Windows (IIS, Windows Services)
+- Other serverless/platform-specific packages may bundle the full tracer similarly
+
 ## Tracer Structure
 
 - `tracer/src/Datadog.Trace` — Core managed tracer library
@@ -299,6 +318,7 @@ The tracer runs in-process with customer applications and must have minimal perf
 - `docs/development/AzureFunctions-Architecture.md` — Azure Functions architecture deep dive
 - `docs/development/Serverless.md` — Serverless instrumentation
 - `docs/development/UpdatingTheSdk.md` — SDK updates
+- `docs/development/QueryingDatadogAPIs.md` — Querying Datadog APIs for debugging (spans, logs)
 
 **CI & Testing:**
 - `docs/development/CI/TroubleshootingCIFailures.md` — Investigating build/test failures in Azure DevOps