starknet_transaction_prover: add CORS and config validation tests

[avi-starkware]

Summary

• Add 8 CORS tests: layer construction for empty/wildcard/allowlist, mode label correctness, origin normalization edge cases (ftp scheme, missing host, userinfo, default port stripping)
• Add 10 config validation tests: missing rpc_url, zero max_concurrent/max_connections, CORS mutual exclusivity, fee validation toggle, config file loading/merging, CLI override precedence, non-HTTP CORS scheme rejection

Test plan

• SEED=0 cargo test -p starknet_transaction_prover -- cors_test — 13 tests pass
• SEED=0 cargo test -p starknet_transaction_prover -- config_test — 33 tests pass (includes pre-existing)

🤖 Generated with Claude Code

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Note

Low Risk
Test-only changes plus a #[cfg(test)] module include; no runtime logic changes beyond exercising existing validation paths, so risk is low.

Overview
Adds new unit tests for ServiceConfig::from_args covering required-field enforcement, numeric argument validation, --no-cors/--cors-allow-origin exclusivity, fee validation toggling, and config-file vs CLI precedence.

Introduces a dedicated cors_test.rs (wired via #[cfg(test)] in cors.rs) to validate CORS layer construction, mode labeling, and origin normalization edge cases (schemes/host/userinfo/default-port handling).

^{Written by Cursor Bugbot for commit 1b5cafe. This will update automatically on new commits. Configure here.}

[reviewable-StarkWare]

This change is 

[avi-starkware]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• starknet_transaction_prover: add CORS and config validation tests #13136 👈 (View in Graphite)
• starknet_transaction_prover: add exhaustive error enum and error mapping tests #13135
• starknet_transaction_prover: add committer utils unit tests #13134 : 1 other dependent PR (#13365 )
• starknet_transaction_prover: add prover input validation unit tests #13133
• starknet_transaction_prover: add exhaustive error enum and mapping tests #13369
• starknet_transaction_prover: sanitize error messages returned to clients #13132
• starknet_transaction_prover: add ConfigMap docs and full config reference #13167
• starknet_transaction_prover: add external developer docs #13129
• starknet_transaction_prover: validate request inputs before proving #13125
• main-v0.14.2

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