chore: rename drift-labs GitHub URLs to velocity-exchange

[ChesterSim]

Part of renaming the GitHub org drift-labs -> velocity-exchange.

DRAFT — do not merge until the velocity-exchange org (and, where applicable, the @velocity-exchange npm scope) exists; old URLs currently redirect.

URL forms changed

• github.com/drift-labs/ → github.com/velocity-exchange/ (in .cargo/config.toml, programs/drift_vaults/Cargo.toml, Cargo.lock, README.md, CHANGELOG.md, .github/workflows/on-sdk-update.yml)
• @drift-labs/ npm scope → @velocity-exchange/ (in package.json, ts/sdk/package.json, all test imports under tests/, all SDK source imports under ts/sdk/src/ and ts/sdk/cli/, .eslintrc.js, yarn.lock, ts/sdk/yarn.lock)

Total: 94 substitutions across 49 files.

Skipped (upstream-Drift historical refs)

• AUDIT.md:1: Links to github.com/drift-labs/audits presenting a historical Neodyme audit of the original Drift Vaults project — this is a historical/credit reference to a separate org's audit repo, not a live dependency or this repo's own resource.

Warning: @velocity-exchange npm scope

The @drift-labs/sdk dependency (used extensively in imports across tests and SDK source) and the @drift-labs/vaults-sdk package name have been renamed to @velocity-exchange/sdk and @velocity-exchange/vaults-sdk respectively. Builds will break until those packages are republished under the @velocity-exchange npm scope. Do not merge until @velocity-exchange/sdk is available on the npm registry.