perf(exec): add correlated diagnostics and reuse grants

[realmroot]

Summary

• add --log-level and REALMROOT_LOG_LEVEL diagnostics on stderr
• correlate HTTP requests across Realmroot and Resource Servers without logging secrets or query values
• report discovery, authorization, broker, child-process, and HTTP timings
• retain protocol scopes and learn a successful native operation binding to avoid repeated challenge/approval work

Review environment acceptance

Build the CLI and run realmroot --log-level debug exec github --context saltbo -- gh api rate_limit, followed by realmroot --log-level debug exec cloudflare -- wrangler whoami. Confirm both commands succeed, repeated GitHub execution does not receive another insufficient-scope challenge, and each command emits one correlation ID with phase timings.

Verification

• go test ./...

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_{🤖 Created by Jarvis via Realmroot}