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
Pure refactor that centralizes an existing middleware chain; HTTP and HTTPS behavior should stay identical if the macro matches the prior stacks.

Overview
Introduces prover_http_middleware! in server.rs so the plain HTTP (start_server) and HTTPS (tls::start_tls_server) JSON-RPC paths share one tower middleware chain instead of two copy-pasted ServiceBuilder blocks.

Both transports now call prover_http_middleware!(cors_layer, ohttp_layer); layer order is unchanged (health outermost, OHTTP outside compression, body mapping around OHTTP). The long inline comments in each path are replaced by a single doc comment on the macro (including why a macro is used and why it must sit above pub mod tls).

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