starknet_transaction_prover: per-request structured log with request-id

[avi-starkware]

Adds RequestLogLayer that emits one event="http_request" log line per
request with request_id, method, path, status, and latency_ms. The id is
accepted from x-request-id or generated as a 128-bit random hex string,
and is echoed back on the response so callers can quote it. No request
body bytes are inspected (transaction calldata is private user data).

Co-Authored-By: Claude Opus 4.7 (1M context) noreply@anthropic.com

[cursor]

PR Summary

Low Risk
Observability-only middleware on the HTTP envelope with explicit OHTTP privacy constraints and input sanitization; no changes to proving or auth logic.

Overview
Adds RequestLogLayer as the outermost tower middleware on the transaction prover HTTP/HTTPS stacks (via prover_http_middleware!), so each request gets one structured event="http_request" log with method, path (truncated for logging only), status, latency_ms, and a request id.

The id comes from x-request-id when it passes validation (length cap, printable ASCII only) or is generated as UUID v4; it is set on the forwarded request and echoed on the response. Request bodies are not read. Docs in the layer explain why this id is not propagated into downstream spans for OHTTP (envelope vs. decapsulated content unlinkability).

Workspace uuid dependency is added; unit tests cover echoing, generation, and rejecting hostile/oversize ids.

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Learn more

• starknet_transaction_prover: log resolved config at startup (secrets redacted) #14684
• starknet_transaction_prover: document observability surface in README #14203
• starknet_transaction_prover: origin-level breadcrumbs for validation errors #14172
• starknet_transaction_prover: /health returns 503 when service is saturated #14171
• starknet_transaction_prover: bump prover_panics_total on panic hook fire #14170
• starknet_transaction_prover: HTTP request count + latency + in-flight metrics #14169
• starknet_transaction_prover: proving-job duration + outcome metrics #14168
• starknet_transaction_prover: Prometheus /metrics endpoint with build_info #14167
• starknet_transaction_prover: global panic hook + graceful SIGTERM shutdown #14166
• starknet_transaction_prover,tower_ohttp: OHTTP-unlinkable request-id for decapsulated content #14222
• starknet_transaction_prover: per-request structured log with request-id #14165 👈 (View in Graphite)
• starknet_transaction_prover: unify HTTP middleware stack via macro #14286
• main-v0.14.3

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