pk-doctor: mcp_config_drift / server_header_drift suggested_fix references nonexistent script in derived projects

[projectious]

Summary

Three pk-doctor checks emit suggested_fix: uv run scripts/generate-mcp-manifest.py (or equivalent for preauth regen), but that script does not exist in derived projects — only upstream processkit ships it. So the suggested remediation is unreachable from within the project.

Affected finding ids

• `mcp_config_drift.manifest-stale` (WARN)
• `server_header_drift.coverage-mismatch` (WARN)
• `preauth_applied.spec-drift` (WARN)

Repro

Fresh ai-market-research checkout, just applied MIG v0.26.14→v0.27.1:

```bash
$ find . -name "generate-mcp-manifest*"

(no results)

$ find . -name "preauth*" -path "scripts"

only test data / templates, no regenerator

```

`pk-doctor` says "run scripts/generate-mcp-manifest.py" — there's nothing to run.

Expected

One of:

1. Ship the regenerator scripts to derived projects as part of v0.27.x — bundle them in `context/skills/processkit//scripts/` and update suggested_fix paths.
2. Expose regeneration as an MCP tool (e.g. `regenerate_mcp_manifest`, `regenerate_preauth`) so derived projects can call it via the gateway.
3. Update suggested_fix text to point at the actual remediation path (e.g. "upgrade processkit to vX.Y which ships these regenerators" or instructions to copy from upstream).

Impact

Three findings the user cannot actionably resolve from within a derived project, despite being marked actionable + requiring user confirmation. Blocks pk-doctor from reaching 0 WARN.