Bump OTel deps and cut over to check run span IDs

[krzko]

Summary

• Add AGENTS.md for coding agents working in this repo
• Bump go-github (v60 to v78), OTel (v1.26 to v1.44), and semconv (v1.20.0 to v1.41.0)
• Derive job and step span IDs from the job's GitHub check run ID, matching the OpenTelemetry Collector GitHub Actions Receiver's current default scheme (receiver.githubreceiver.UseCheckRunID). This replaces the old runID plus attempt plus job plus step hash and is a breaking change for correlation with receivers older than collector-contrib v0.151.0
• Add cicd.* and vcs.* semantic convention attributes to the command span

Test plan

• go build, go vet, go mod tidy all pass
• Cross compiled linux-amd64 and darwin-arm64 with the updated deps, verified upx compression still works on linux (upx 5.2.0 refuses macOS binaries by default now, separate from this change)
• No existing test suite to run against