backfill --config ignores the path when loading the publish config #710

Problem

packages/release/src/commands/backfill-command.ts:92 calls @releasekit/publish's loadConfig(cwd, options.config), but that function takes a single { cwd, configPath } object. The cwd string lands in the options slot, so configPath is undefined and the publish config comes from the default lookup: releasekit backfill --config <path> ignores the path for publish settings. (cwd is process.cwd() anyway, so only --config is lost.)

The notes call on the line above is correct: notes' loadConfig takes (projectDir, configFile).

Typecheck doesn't catch it, because @releasekit/publish's built declarations type its exports as any for other packages (dist/index.d.ts re-exports from ./config.ts and other .ts files that aren't in dist).

Found while reviewing #690.

Fix

Call loadPublishConfig({ cwd, configPath: options.config }), and add a test that backfill --config <path> reads that file's publish settings.