docs(kyberforge): narrow issue #89 scope, migrate CC platform facts to apm-workflow

A grill-me session determined plugin-author/marketplace-author are fully
superseded by the landed apm-install/apm-workflow/apm-orchestrate artifacts
and will be deleted (not adapted) under issue #90, narrowing issue #89 to
skill-author/agent-author only; forge stays untouched. ADR-0015 is amended
to record this correction plus a three-way content-migration audit.

Claude Code platform-constraint facts that lived only in
plugin-author/marketplace-author (reserved name prefixes, the ADR-0010
agents/ stray-.md validator gotcha, claude plugin validate as a terminal
check, and a removal/re-pack confirm-before-proceeding note) remain true
post-conversion and are migrated into apm-workflow's reference docs via
kyberforge:skill-author, which also updated the skill's README and
sources.md provenance records. Dual-manifest-specific conventions (ADR-0006
parity, CC/Copilot field-placement split) do not carry forward since they
no longer apply.

ADR: 0015

plugins/kyberforge/skills/apm-workflow/references/compile.md

@@ -42,3 +42,7 @@ apm run <script> [--param key=value]
 ```
 
 Executes a named script defined under `scripts:` in `apm.yml`, with `--param` substituting values into the script's parameters.
+
+## Gotchas
+
+- `claude plugin validate --strict` auto-scans every `.md` file directly under a compiled plugin's `agents/` directory and treats it as an agent definition requiring frontmatter, independent of any manifest declaration (this repo's own empirically-tested finding — see ADR-0010). A non-agent `.md` file (notes, provenance record, README) that ends up under `.apm/agents/` in the source tree will still fail validation once compiled to the `claude` target. Keep such files outside `.apm/agents/` (e.g. at the package root), regardless of what `apm.yml` declares.