Remove the forbidden `workflow_path` frontmatter variable from 16 step files
across 3 workflows (quick-dev, quick-spec, check-implementation-readiness).
Per BMAD workflow standards, step files should use relative paths or
{project-root} references instead.
Changes:
- quick-dev (6 files): removed workflow_path and unused thisStepFile
- quick-spec (4 files): removed workflow_path, updated templateFile to use relative path
- check-implementation-readiness (6 files): removed workflow_path, updated all references to use relative paths
Also fixes incorrect path in check-implementation-readiness that referenced
non-existent 'implementation-readiness' folder instead of 'check-implementation-readiness'.
Fixes#1546
Brian Madison