Fix harness-kit router dependency range

[khaliqgant]

Summary

• bump @agentworkforce/harness-kit to 0.5.5 so the bad 0.5.4 package can be replaced
• change the harness-kit workspace dependency on @agentworkforce/workload-router from workspace:* to workspace:^ so pnpm publishes a compatible npm range
• correct the 0.5.4 changelog wording to match the published workload-router version

Verification

• corepack pnpm run check
• corepack pnpm --filter @agentworkforce/harness-kit pack --pack-destination /tmp/workforce-harness-pack
• throwaway npm install of the packed harness-kit tarball resolved @agentworkforce/workload-router@0.5.4 from npm and exposed useRunnablePersona/useRunnableSelection

Note: the throwaway npm install used --userconfig=/dev/null because this machine has a user-level npm before cutoff that hides packages published after 2026-04-25.