feat(automation): integrate .NET instrumentation watcher

[Pittu-Sharma]

Description

This PR establishes the foundation for tracking .NET instrumentation metadata within the OpenTelemetry Ecosystem Explorer by implementing a dedicated .NET watcher.

Since the OpenTelemetry .NET ecosystem does not use a centralized catalog API like other ecosystems, this watcher dynamically traverses the open-telemetry/opentelemetry-dotnet-contrib repository using the GitHub Git Tree API to discover .csproj files and classify them.

Resolves #101.

Changes Made

• Created .NET Watcher: Implemented dotnet_client.py, inventory_manager.py, and instrumentation_sync.py inside ecosystem-automation/dotnet-instrumentation-watcher.
• Registry Initialization: Scaffolded the ecosystem-registry/dotnet/ snapshot directory and enabled versioned schema generation (instrumentation.yaml).
• CI / Automation Integration:
  • Hooked the new watcher into .github/workflows/nightly-registry-update.yml to ensure metadata stays fresh automatically.
  • Added full test coverage for the watcher and linked it to the test-ecosystem-automation runner in .github/workflows/build-and-test.yml.
• Monorepo Stabilization: Removed conflicting __init__.py files across all watcher test suites to resolve pytest discovery errors on Windows. Patched instrumentation_transformer.py in the DB builder to prevent compilation crashes when metadata keys are missing.
• Roadmap Documentation: Added docs/dotnet-integration-roadmap.md mapping out the database and frontend integration tasks.

Testing and Compliance

• All 372 monorepo unit tests pass locally (uv run pytest).
• Python code strictly adheres to project formatting and linting rules (uv run ruff check . and uv run ruff format .).
• Missing copyright headers have been applied and checked (uv run python scripts/check_copyright.py).
• Markdown documentation passes project standards (bun run lint:md).

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[Pittu-Sharma]

Hi, @jaydeluca , Please review the PR once. If any changes are required please let me know.