[persona-kit 6/8] Delete @agentworkforce/harness-kit from monorepo

[willwashburn]

Part of the persona-kit consolidation. Depends on #68. This is issue 6 of 8.

Goal

@agentworkforce/harness-kit has been a re-export shim since #65, since the workforce CLI no longer imports it (#67), and since workload-router doesn't depend on it (#68). Delete the package from the monorepo. Mark the npm package deprecated so external consumers see a migration warning, but do not unpublish — that breaks lockfiles for anyone pinned.

Tasks

• Delete packages/harness-kit/ from the monorepo (the entire directory).
• Remove packages/harness-kit from the workspace registration (root package.json workspaces array, or pnpm-workspace.yaml).
• Remove harness-kit from any monorepo-wide build orchestration (turbo.json, nx.json, lerna.json, TS project references).
• grep across the monorepo for residual references and clean up:
  • @agentworkforce/harness-kit imports → should be zero
  • harness-kit directory references in scripts, docs, READMEs
  • harness-kit mentions in tsconfig project references
• Run pnpm install (or npm install) to refresh the lockfile.
• On npm (separate from this PR — coordinate with whoever has publish rights): `npm deprecate @agentworkforce/harness-kit "Replaced by @agentworkforce/persona-kit. See https://github.com/AgentWorkforce/workforce/issues/64"\` (link to the tracking issue). Do not `npm unpublish` — anyone with the package in their lockfile would break.

Constraints

• harness-kit on npm stays installable for existing pinned consumers; only new consumers see the deprecation warning.
• This PR is mostly file deletions and config cleanup. If anything stops compiling or testing, it means an earlier issue's migration was incomplete — fix that issue, not this one.
• Don't try to write a back-compat re-export package (@agentworkforce/harness-kit-shim or whatever). The user explicitly said no back-compat.

Verification

• pnpm -r build succeeds.
• pnpm -r test passes.
• grep @agentworkforce/harness-kit across the entire repo (including non-package files: scripts, docs, READMEs, CI configs) returns zero hits.
• grep harness-kit (the bare directory name) outside node_modules, lockfiles, and historical CHANGELOGs returns zero hits.
• CI passes end-to-end.
• npm: `npm view @agentworkforce/harness-kit` shows the deprecation message (after the deprecate step runs).

Reference

Plan section 1.6.