refactor: centralize market contract execution

[tvolk131]

Summary

• analyze the canonical SimplicityHL template once per process, instantiate it per market, preserve structured compiler diagnostics, and fail with exact PSET input indices when witness UTXOs are missing
• introduce a typed canonical finalized-spend boundary carrying the decoded redeem node, CMR, typed control block, execution bounds, encoded sizes, and exact minimal budget annex
• remove the duplicate client budget decoder, install all covenant witnesses atomically, and re-execute each exact serialized finalized witness (including its annex) before committing the staged PSET
• migrate client validation, confirmed-spend interpretation, and node registration to typed compiler/execution errors while restricting the generated Program escape hatch to parity tests

The market SimplicityHL source, ABI, scripts, and canonical CMR are unchanged.

Verification

• nix develop .#default --command just fmt-check
• nix develop .#default --command just clippy
• nix develop .#default --command just test — 203 passed, 5 environment-dependent tests skipped; doc tests passed
• nix develop .#default --command just wasm-check
• nix develop .#default --command just verify-smplx
• nix flake check
• targeted typed-finalization, canonical-annex, indexed-UTXO, installed-witness re-execution, CMR/control-block mismatch, and SDK parity regressions

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