fix: enable TLS for OTLP HTTP export

[willkill07]

Overview

Enable TLS support for NeMo Flow's native OTLP/HTTP exporter so direct HTTPS trace endpoints, including internal platform backed Datadog ingestion, work without routing through a local OpenTelemetry collector.

• I confirm this contribution is my own work, or I have the right to submit it under this project's license.
• I searched existing issues and open pull requests, and this does not duplicate existing work.

Details

• Adds the reqwest-rustls feature to the native opentelemetry-otlp dependency.

Validation:

• cargo tree -p nemo-flow -e features -i reqwest --features otel --target x86_64-apple-darwin confirms reqwest/rustls-tls-native-roots is enabled.
• cargo test -p nemo-flow --features otel observability::otel::tests -- --nocapture

Where should the reviewer start?

N/A

Related Issues: (use one of the action keywords Closes / Fixes / Resolves / Relates to)

• Closes NMF-112

Summary by CodeRabbit

• Chores
  • Updated OpenTelemetry OTLP dependency configuration to include Rustls-based HTTP request support for improved TLS/SSL handling in non-WebAssembly environments.

[coderabbitai]

Walkthrough

Single-line dependency feature update in crates/core/Cargo.toml adding reqwest-rustls feature support to the opentelemetry-otlp crate for non-WebAssembly targets, preserving existing reqwest-blocking-client and grpc-tonic features.

Changes

Dependency Configuration

Layer / File(s)	Summary
OpenTelemetry OTLP Feature Addition crates/core/Cargo.toml	The opentelemetry-otlp dependency under target.'cfg(not(target_arch = "wasm32"))'.dependencies now enables the reqwest-rustls feature alongside existing reqwest-blocking-client and grpc-tonic features.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	Title follows Conventional Commits format with 'fix' type, clear scope, and concise imperative summary under 72 characters.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description check	✅ Passed	The PR description follows the required template structure with all sections completed: Overview with required checkboxes, Details explaining the change, Where should the reviewer start, and Related Issues with action keyword.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[bbednarski9]

Double checked that we do not add any new deps with this. LGTM

[willkill07]

/merge