starknet_transaction_prover: unify HTTP middleware stack via macro

[avi-starkware]

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[reviewable-StarkWare]

This change is 

[avi-starkware]

• 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
• starknet_transaction_prover: unify HTTP middleware stack via macro #14286 👈 (View in Graphite)
• main-v0.14.3

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[cursor]

PR Summary

Low Risk
Refactor-only: same middleware layers and order; no auth, TLS, or RPC behavior changes beyond deduplication.

Overview
Unifies the JSON-RPC HTTP middleware stack for plain HTTP (start_server) and HTTPS (tls::start_tls_server) behind a single prover_http_middleware! macro in server.rs, replacing two identical ServiceBuilder chains.

The macro keeps the same layer order (health outermost, OHTTP outside compression, body mapping around OHTTP). Rationale that lived in duplicated comments now lives on the macro, including why it must sit above pub mod tls for macro_rules! visibility in tls.rs.

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