starknet_os: support DeployAccount v4 Blake2 address derivation in the OS

[ron-starkware]

Stack — part 4 of 9 (base: #14813). Targets 0.14.5.

Teaches the proving OS to derive a v4 deploy-account address.

• get_contract_address_blake_escaped in the OS (BLAKE2s + the Pedersen-image escape), verified from hints rather than computing a Legendre symbol in-circuit: a skipped candidate needs a square root of t(lift), the final candidate a square root of t(address)/3 (3 is a fixed quadratic non-residue). One field-mul per witness; a wrong witness fails the proof, so the hint cannot move the address.
• prepare_constructor_execution_context dispatches on the hinted tx_version. That hint is bound by the transaction-hash assertion — both the version felt and the derived address are in the committed preimage.
• get_account_tx_common_fields takes the version (was hardcoded 3); the deploy-account tx-hash, deprecated-fields-consistency and max-fee asserts are relaxed from = 3 to (v-3)(v-4) = 0.
• The Cairo↔Rust parity test asserts the OS derivation equals starknet_api's Blake2 arm, escape included.

Versioned constants (0.14.5 only): extending those shared version guards costs a few steps per transaction even for v3 — execute_txs_inner DeployAccount 4989→5017, InvokeFunction 4779→4787, Declare 3938→3946 — which is the normal consequence of adding a transaction version through shared gates. blockifier_versioned_constants_0_14_4.json and the 0.14.3→0.14.4 diff fixture are byte-identical to main; the deltas land in 0_14_5 and its diff fixture. allowed_virtual_os_program_hashes keeps 0x1c7be3… (baked into the frozen stwo proof fixtures) and replaces only the other slot.

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• starknet_os_flow_tests: prove a block with a DeployAccount v4 end-to-end #14819
• apollo_starknet_os_program,starknet_os: add the deploy_v2 syscall to the OS #14818
• blockifier: add the deploy_v2 syscall (Blake2 contract address derivation) #14817
• apollo_http_server,apollo_gateway_types: accept DeployAccount v4 at the gateway #14816
• blockifier: enable DeployAccount v4 execution #14815
• starknet_os: support DeployAccount v4 Blake2 address derivation in the OS #14814 👈 (View in Graphite)
• starknet_api: add DeployAccount v4 transaction type (Blake2 address derivation) #14813
• starknet_api: escape the Pedersen image in Blake2 contract address derivation #14812
• starknet_api: make contract address derivation hash-pluggable #14811
• main

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