feat: add core telemetry and trace tooling

[muscariello]

Summary

• add core OpenTelemetry init, spans, and file logging
• add shadictl trace subcommand for local trace inspection
• document telemetry configuration and local traces

Testing

• cargo build
• just docs-build

[codecov]

Codecov Report

❌ Patch coverage is 71.48760% with 138 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
crates/shadictl/src/main.rs	74.43%	79 Missing ⚠️
crates/shadi_telemetry/src/lib.rs	61.84%	58 Missing ⚠️
crates/shadi_sandbox/src/lib.rs	95.65%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!

[msardara]

LGTM ✅