test: add integration test for consolidate unspents

[danielpeng1]

Adds end-to-end consolidateUnspents integration tests for tbtc in local and external signing modes.

• New consolidateUnspents.integ.test.ts where external and local suites check a 200 response (txid, tx, status, transfer), the key provider call (POST /sign vs GET /key/:pub), BitGo POST /consolidateUnspents with feeRate/maxFeeRate/minValue/txFormat, and POST /tx/send with type: 'consolidate'. Confirms tx/build is never called (consolidate goes directly to /consolidateUnspents).
• New prebuildTx.consolidate.tbtc.json, using real PSBT from test keypairs (2 p2wsh inputs, 1 change-only output) so SDK verifyTransaction passes; tests PSBT magic bytes on key provider signablePayload.
• Extended mockBitgoServer.ts by adding POST /consolidateUnspents route and consolidatePrebuildTx fixture slot in the coin registry (tbtc uses the new consolidate fixture; EVM coins fall back to their standard prebuild).

Also updated the accelerate integration test in similar vein, since I thought we could make my original fixture + associated test more robust.

• Changed prebuildTx.accelerate.tbtc.json from simple emptyish stub to a full PSBT with real input/output data matching the test keypairs; accelerate.integ.test.ts gets body checks for signablePayload magic bytes, transfer shape, and cpfpTxIds/txHex on tx/send.

Tests pass (npm run docker:test:integration shown here):

Ticket: WCN-764

[linear-code]

WCN-764

[vinhkhangtieu]

add integ test. Also need eyes from other wallet member as I need to learn more about the context of this pr

[pranishnepal]

🚀