Bifrost: Hold vault lock through broadcast & add RPC context deadlines

ZlyDevMayarequested to merge
zlyzol/thornode:zoly/fix/utxo-vault-lock-broadcast-timeout into develop

Closing in favor of !4596 (merged).

Reason: same changes were reopened from an upstream source branch instead of a fork. Please continue review/discussion in !4596 (merged).

Summary

This MR improves UTXO signing safety and RPC resilience, and aligns ZEC/BTC RPC client interfaces so one shared client abstraction can be used.

Problem

  • Vault-level locking did not consistently cover the full sign -> broadcast window, which can allow concurrent UTXO selection/broadcast races.
  • UTXO RPC wrapper calls did not consistently enforce context deadlines.
  • rpc.Client and zec.Client had mismatched interfaces, forcing split fields and chain-specific branching.
  • Simulation code still used the old rpc.NewClient signature.

Changes

  • Hold vault lock through broadcast in UTXO consolidate flow and signer flow (via lock-capability interface) to eliminate local double-spend risk on concurrent work.
  • Add timeout-aware context handling to UTXO RPC wrapper calls (Call and batch paths).
  • Pass configured HTTP timeout into UTXO RPC client creation.
  • Add CallContext and BatchCallContext to zec.Client.
  • Introduce a shared rpcClient interface (Call, BatchCall, CallContext, BatchCallContext) and use a single client field for both standard RPC and ZEC RPC implementations.
  • Update simulation UTXO constructor call to match new RPC client signature.

Impact

  • Safer concurrent signing/broadcast behavior for UTXO vaults.
  • Better failure behavior on slow/stuck RPC calls via deadlines.
  • Less duplicated chain-conditional RPC code and cleaner client abstraction.

Test plan

  • make test passes
  • make lint passes
  • make test-simulation passes
Edited by ZlyDevMaya

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