nightly-20260404

feat: migrate forc-client nightly builds to forc monorepo (#83)

`forc-client` moved from `FuelLabs/sway` to `FuelLabs/forc` as of v0.71.0
(see https://github.com/FuelLabs/forc/pull/143). This PR updates nightly
builds to source it from the new location.

Changes:
- Add `forc-client` to the forc monorepo workflow
- Handle multi-binary crates by extracting names from [[bin]] sections
- Remove `forc-deploy`, `forc-run`, `forc-submit`, `forc-call` from sway workflow
- Update README to document the new source

Part of the tooling monorepo migration: https://github.com/FuelLabs/sway-rfcs/pull/49