Expose SwapScript constructors from raw scripts, extract verify_submarine_preimage

[i5hi]

The validated cooperative-claim helper (SwapScript::submarine_cooperative_claim, which verifies the server's preimage against the invoice payment hash before partial-signing) was only reachable from a fresh swap response. Bindings that reconstruct swap scripts from storage (boltz-dart) could not use it, so they re-implemented the coop close against the raw primitives — skipping the preimage check and partial-signing whatever transaction hash the server supplies.

• SwapScript::from_bitcoin / SwapScript::from_liquid: build the wrapper from an already-reconstructed script, so the validated helpers are reachable for restored swaps.
• verify_submarine_preimage extracted from submarine_cooperative_claim (behavior unchanged) so the proof-of-payment gate is a pure, unit-testable function.
• 3 unit tests using an invoice minted and signed in-test: matching preimage accepted, mismatch rejected, bad hex rejected.

Validated: cargo test --lib wrappers green; full submarine regtest suite green against the local regtest stack (4/4, including the cooperative claim path end to end). The pre-existing swaps::boltz::tests failures hit the public api.boltz.exchange (currently down) and are unrelated.

Companion PR: SatoshiPortal/boltz-dart (coop_close_submarine delegates to the validated flow).

Includes the CI fixes from #165 (committed Cargo.lock, ignored live-API tests, wasm lock seeding) so checks can run while that PR is open — its diff collapses to the wrappers change once #165 merges.