docs: expand README quickstart examples

[leo1987820]

Summary

• rewrites the README quickstart with concrete setup, connection, escrow creation, release, pagination, multisig, utility, and error-handling examples
• removes broken/garbled README headings and replaces them with plain Markdown sections
• exports TrustFlowClient from the package root so the documented import path works

Fixes #13.

Verification

• npm test -- --runInBand (16 suites, 90 tests passed)
• npm run build
• npm run lint (0 errors; existing warnings remain)

Note: npm ci currently fails because the upstream package-lock.json is out of sync with package.json; I used npm install --package-lock=false --ignore-scripts locally to install dependencies without changing the lockfile before running the checks above.