fix(kyberforge): bridge apm content to Claude Code's flat plugin discovery

Claude Code's (and Copilot's) native plugin installer has zero awareness of
.apm/ nesting -- it convention-scans only flat skills/, agents/, commands/,
hooks.json at each plugin's root. Confirmed via strings on the installed
claude binary and live installs of git@holocron/gitea@holocron/kyberforge@
holocron, all reporting Skills(0) Agents(0) Hooks(0) post ADR-0015's apm
conversion. Root cause (apm_cli/core/plugin_manifest.py): apm's plugin.json
compiler deliberately strips skills/agents/commands keys, assuming the host
already auto-discovers those convention directories -- it has no model of
.apm/ being host-visible at all. Separately, apm's own bundle exporter
(apm_cli/bundle/plugin_exporter.py, behind `apm pack --format plugin`)
implements the correct .apm/ -> flat mapping, but only ever targeted
build/<name>-<version>/, a path nothing in marketplace.json's source: points
at.

scripts/sync-plugin-content.sh wraps that bundle exporter and copies its
agents/, skills/, commands/, instructions/, extensions/, and merged
hooks.json back into each plugin's own root as a second tracked
compiled-output category -- same governance status as
.claude-plugin/plugin.json: generated from .apm/, never hand-edited. tests/
subdirectories are excluded from the mirror (dev fixtures, not host-visible
runtime content; several hardcode a relative repo-root walk-up sized for the
.apm/-nested depth, which breaks when duplicated one level shallower).
Applied for real across all 6 plugins and verified two ways: `claude plugin
validate --strict` passes on every real plugin directory, and a live
`claude --plugin-dir <path> -p "list skills/agents"` behavioral test
confirms content is now actually discovered.

Also, from the same issue #90 review round:
- scripts/check-manifests.sh pointed at each plugin's root-level plugin.json
  (checking skills/hooks/mcpServers/agents pointer fields) -- that file was a
  stale near-duplicate of .claude-plugin/plugin.json nothing else read or
  wrote, now deleted across all 6 plugins. check-manifests.sh is rewritten to
  validate .claude-plugin/plugin.json instead, and drops the pointer-field
  checks entirely (nothing to check -- those fields are correctly absent by
  design). Content-presence drift is now check-plugin-content-sync's job, a
  new pre-push hook wired in .pre-commit-config.yaml.

docs/adr/0017 records the root cause and decision in full, including two
rejected alternatives (patching plugin.json's path fields directly -- apm's
compiler strips them on every run; pointing marketplace.json at apm pack's
build/ output -- a version-suffixed non-source directory nothing can install
from without an extra build step). ADR-0015 and CONTEXT.md are updated to
point at it.

Refs: #90

plugins/kyberforge/skills/agent-audit/README.md

@@ -0,0 +1,57 @@
+# agent-audit
+
+Audits an agent definition for correctness and quality — a single vendor-neutral file at
+plugin/APM scope, or a Claude Code and Copilot file pair at project/user scope.
+
+## What it does
+
+At **plugin/APM scope**, accepts the single `.apm/agents/<name>.agent.md` file — there is no
+counterpart. Structural checks via `validate.sh` hard-`FAIL` any frontmatter field outside the
+vendor-neutral allowlist (`name`, `description`, `model`, `source_keys` — the last for
+provenance tracking, checked separately by `validate-provenance.sh` against `sources.md`; see
+ADR-0016), since `apm compile`
+copies frontmatter verbatim to both harnesses and an unsafe field can't be silently dropped for
+just one of them.
+
+At **project/user scope**, accepts either file in a CC `.md` / Copilot `.agent.md` pair, derives
+the counterpart automatically, and validates both. Runs structural checks via `validate.sh`
+(required fields, kebab-case name, no placeholders, no CC-only fields in the Copilot file, no
+Copilot-only fields in the CC file), provenance chain validation via `validate-provenance.sh`
+(checks `source_keys` against `sources.md` at the plugin root — plugin/APM scope only), then
+qualitative checks on description phrasing and system prompt quality. Step 1 also runs a
+Vale-based prose sub-check via `vale-wrap.sh` against both files of the pair, using the
+`Kyberforge` style (both files) and `KyberforgeCopilot` style (Copilot file only) — every alert
+is a `FAIL`, cited by rule ID — falling back to Step 2 judgment when the `vale` binary is
+unavailable or reports `0 files` scanned. Produces a compact findings report in the same format
+as `skill-audit`.
+
+## Usage
+
+```
+/agent-audit
+```
+
+Pass the path to either agent file as the argument.
+
+## Files
+
+| File | Purpose |
+|------|---------|
+| `SKILL.md` | Skill instructions for agents |
+| `assets/vale/.vale.ini` | Vale config: scopes `Kyberforge` to `**/agents/*.md`, `Kyberforge`+`KyberforgeCopilot` to `**/*.agent.md` |
+| `assets/vale/styles/Kyberforge/DescriptionOpener.yml` | Flags descriptions opening with "This skill/agent" instead of an imperative "Use when..." |
+| `assets/vale/styles/Kyberforge/PaddingPhrase.yml` | Flags generic "see references/ for info" pointers instead of specific file references |
+| `assets/vale/styles/Kyberforge/SentenceOpenerThereIs.yml` | Flags sentences opening with "There is/are" instead of naming the subject directly |
+| `assets/vale/styles/Kyberforge/VagueWording.yml` | Flags vague capability wording ("helps with", "utilize", "assists with", "used for") in descriptions |
+| `assets/vale/styles/KyberforgeCopilot/ProactivePhrase.yml` | Flags CC-specific "Use proactively" phrasing with no effect in Copilot descriptions |
+| `references/README.md` | Directory documentation for references/ |
+| `references/description-quality.md` | Qualitative guide for borderline description findings |
+| `references/field-inventory.md` | Authoritative list of valid CC and Copilot agent fields |
+| `references/sources.md` | Research provenance for skill content |
+| `scripts/README.md` | Directory documentation for scripts/ |
+| `scripts/validate.sh` | Structural validation script for agent file pairs |
+| `scripts/validate-provenance.sh` | Provenance chain validation script for agent pairs against `sources.md` (plugin root) |
+| `scripts/vale-wrap.sh` | Drop-in `vale` wrapper that works around a frontmatter-description NLP scope limitation |
+| `tests/README.md` | Bats test dependency and run instructions |
+| `tests/validate.bats` | Bats tests for validate.sh |
+| `tests/validate-provenance.bats` | Bats tests for validate-provenance.sh |