fix(gateway-interceptors): configure connect timeout and HTTP/2 keepalive on interceptor gRPC channel

[letv1nnn]

Summary

The interceptor gRPC channel was dialed bare — Endpoint::from_shared(...).connect() with no connect timeout and no HTTP/2 keepalive. These channels are long-lived: ExecutionPlan::load dials once at startup and the resulting Channel is cloned into every BindingPlan and GatewayInterceptorProfileSource for the process lifetime. With no keepalive, an idle-reaping hop, load-balancer timeout, interceptor redeploy, or GOAWAY silently invalidated the connection, and the failure only surfaced on the next interceptor evaluation. With no connect timeout, an unreachable interceptor host could hang on the OS default TCP connect timeout.

This applies the repo-standard channel tuning (matching openshell-core and openshell-sdk) to both the TCP and unix-socket interceptor channels, so idle connections survive intermediary idle timeouts, dead peers are detected proactively, and dials are bounded.

Related Issue

Closes NVIDIA#2612.

Changes

• Add tune_endpoint helper in crates/openshell-gateway-interceptors/src/plan.rs applying connect_timeout(10s),
  http2_keep_alive_interval(10s), keep_alive_while_idle(true), keep_alive_timeout(10s), and
  http2_adaptive_window(true).
• Route connect_endpoint (TCP) and connect_unix_endpoint (unix socket) through tune_endpoint instead of dialing a bare endpoint.

Testing

• mise run pre-commit passes
• Unit tests added/updated
• E2E tests added/updated (if applicable)

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)
• Architecture docs updated (if applicable)

Summary by CodeRabbit

• Performance & Reliability
  • Improved interceptor gRPC connection reliability with a 10-second connection timeout.
  • Added HTTP/2 keepalive settings to help maintain stable connections.
  • Enabled adaptive flow control for improved communication performance across supported connection types.

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📝 Walkthrough

Walkthrough

The interceptor plan adds shared endpoint tuning for regular and Unix-socket gRPC connections. The tuning sets a 10-second connect timeout, HTTP/2 keepalive options, and adaptive flow-control windows.

Changes

Interceptor endpoint tuning

Layer / File(s)	Summary
Apply shared endpoint tuning crates/openshell-gateway-interceptors/src/plan.rs	Regular and Unix-socket interceptor connections apply shared timeout, keepalive, and adaptive flow-control settings before connecting.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: derekwaynecarr, maxamillion, mrunalp

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main changes to interceptor gRPC channel connection timeouts and HTTP/2 keepalive settings.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
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.

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