backfill --config is ignored for the publish config #689

Problem

packages/release/src/commands/backfill-command.ts calls @releasekit/publish's loadConfig(cwd, options.config), but that function takes one LoadOptions object (packages/publish/src/config.ts). The cwd string lands in the options slot and options.config is dropped, so backfill --config <path> loads the publish config from the default location.

It still typechecks because @releasekit/publish's dist/index.d.ts re-exports from ./config.ts, which isn't in dist, so the call's types resolve loosely.

Proposal

• Call loadConfig({ cwd, configPath: options.config }) (matching however LoadOptions names the path).
• Fix the .d.ts re-export so a wrong call signature fails typecheck.
• Test: backfill --config with a non-default path reads that file's publish block.