Add enclave host execution telemetry

[cfal]

Adds OpenTelemetry metrics to the Nitro enclave host. The host now reports execution latency, total in-flight executions, and per-workflow active state, using static environment-provided authentication and graceful client shutdown.

[github-actions]

AI dashboard check

@cfal the AI Stupid Level dashboard is not currently showing any tracked models at score 55 or lower in the last 24 hours.

Tracked models currently not flagged

• GPT-5.4: gpt-5.4 (score 62, status warning, trend down)
• Claude Opus 4.5: claude-opus-4-5-20251101 (score 63, status warning, trend down)
• Claude Opus 4.6: claude-opus-4-6 (score 68, status good, trend stable)
• Claude Opus 4.7: claude-opus-4-7 (score 69, status good, trend up)
• Claude Sonnet 4.5: claude-sonnet-4-5-20250929 (score 62, status warning, trend up)
• Claude Sonnet 4.6: claude-sonnet-4-6 (score 65, status good, trend stable)

To rerun this check on demand, comment /rerun-ai-dashboard-warning on this PR.

Snapshot: 2026-07-21T10:33:03.953Z from https://aistupidlevel.info (24h view).

[github-actions]

👋 cfal, thanks for creating this pull request!

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Once you're ready, you can mark it as "Ready for review" to request feedback. Thanks!

[vreff]

nit: this could be an argument/envar

[vreff]

@cfal there seems to be a vulnerability in the PR.

<h1>Dependency Review</h1>
The following issues were found:<ul><li>❌ 1 vulnerable package(s)</li></ul>
See the Details below.<h2>Vulnerabilities</h2>
<h4><em>enclave/nitro/host/go.mod</em></h4>
<markdown-accessiblity-table data-catalyst="">
Name | Version | Vulnerability | Severity
-- | -- | -- | --
google.golang.org/grpc | 1.80.0 | gRPC-Go: xDS RBAC and HTTP/2 Vulnerabilities | high

</markdown-accessiblity-table>
<blockquote>Only included vulnerabilities with severity <strong>high</strong> or higher</blockquote>Dependency Review
The following issues were found:

    ❌ 1 vulnerable package(s)

See the Details below.
Vulnerabilities
enclave/nitro/host/go.mod
Name	Version	Vulnerability	Severity
[google.golang.org/grpc](https://github.com/grpc/grpc-go)	1.80.0	[gRPC-Go: xDS RBAC and HTTP/2 Vulnerabilities](https://github.com/advisories/GHSA-hrxh-6v49-42gf)	high

    Only included vulnerabilities with severity high or higher