docs(kyberforge): fix path drift and content gaps from apm conversion

The apm conversion (5e23250) moved skills/agents to plugins/<name>/.apm/
and deleted plugin-author/marketplace-author, but a review against issue
#90's Definition of Done found several stale pre-conversion references
left behind by straight git-mv's, plus one real content gap:

- ADR-0014 still documented the old flat vale-prefilter paths in 6
  places, despite ADR-0015 claiming it had been updated.
- ADR-0015 also overclaimed: it said ADR-0014 had both a skills/ and an
  agents/ path regex updated, but ADR-0014 never had an agents/ path
  regex to begin with (its one "agents" mention is a Vale glob-section
  identifier, not a filesystem path). Corrected the wording.
- CONTEXT.md's Skill glossary entry, its Vale-prefilter section, and its
  plugin-author/marketplace-author forward-pointer all still described
  the pre-conversion layout or a "pending issue #90" state that has since
  landed.
- LESSONS.md and two skill test READMEs pointed at skill-author/
  skill-audit/agent-author paths without the .apm/ segment.
- apm-workflow/references/marketplace.md cited plugin-author/SKILL.md's
  Gotchas for the Claude Code reserved plugin-name-prefix list, but that
  list was never actually carried into apm-workflow during the
  conversion despite ADR-0015 claiming it was. Recovered the list from
  git history and inlined it directly rather than leaving a dangling
  citation.
- agent-author/references/deployment-modes.md had an example
  contradicting its own stated .apm/agents/ convention two lines above.

Refs: #90

docs/adr/0015-apm-replaces-plugin-marketplace-authoring.md

@@ -107,9 +107,10 @@ correction) sorted what they document into three buckets:
   living at `plugins/<name>/.apm/agents/*.agent.md` — the directory path changed; the pre-existing
   `.agent.md` extension convention (ADR-0005/ADR-0010) and project/user scope are unaffected, per
   ADR-0016.
-- ADR-0014 (Vale prefilter ships from the plugin) had its hardcoded path regexes
-  (`plugins/<name>/skills/...`/`plugins/<name>/agents/...`) updated for the `.apm/` nesting as part
-  of issue #90's execution.
+- ADR-0014 (Vale prefilter ships from the plugin) had its hardcoded `plugins/<name>/skills/...`
+  paths (the Vale prefilter is skill-scoped only; ADR-0014 never referenced a
+  `plugins/<name>/agents/...` path) updated for the `.apm/` nesting as part of issue #90's
+  execution.
 - `kyberforge` gained three new artifacts (issue #88) before any conversion of existing content
   happened, then lost two (`plugin-author`/`marketplace-author`, deleted once issue #90 verified
   parity) — net version bump 1.3.1 → 1.4.0. The root marketplace catalog bumped 0.3.1 → 0.3.2 to