feat(core): add agentsmd-audit skill files

The previous commit only landed the research-folder rename — a multi-path
git add silently failed and left CONTEXT.md, ADR-0012, and the actual skill
files unstaged. This lands them: the agentsmd-audit skill itself (three
deterministic validators for secrets, structure, and drift against a target
repo's AGENTS.md), its bats test suite, provenance record, and the
CONTEXT.md/ADR entries documenting why this lives in core rather than
kyberforge.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

plugins/core/skills/agentsmd-audit/tests/validate-structure.bats

@@ -0,0 +1,76 @@
+#!/usr/bin/env bats
+
+setup() {
+    REPO_ROOT="$(cd "$BATS_TEST_DIRNAME/../../../../../" && pwd)"
+    load "$REPO_ROOT/tests/test_helper/bats-support/load"
+    load "$REPO_ROOT/tests/test_helper/bats-assert/load"
+
+    SCRIPT="$(cd "$BATS_TEST_DIRNAME/../scripts" && pwd)/validate-structure.sh"
+    TMPDIR="$(mktemp -d)"
+}
+
+teardown() {
+    rm -rf "$TMPDIR"
+}
+
+@test "fails on an empty AGENTS.md" {
+    : > "$TMPDIR/AGENTS.md"
+    run bash "$SCRIPT" "$TMPDIR"
+    assert_failure
+    assert_output --partial "empty"
+}
+
+@test "fails on an unfilled placeholder AGENTS.md" {
+    cat > "$TMPDIR/AGENTS.md" <<'EOF'
+# AGENTS.md
+
+## Setup
+FILL IN: describe setup commands here.
+EOF
+    run bash "$SCRIPT" "$TMPDIR"
+    assert_failure
+    assert_output --partial "placeholder"
+}
+
+@test "passes with INFO on real content missing an optional section" {
+    cat > "$TMPDIR/AGENTS.md" <<'EOF'
+# AGENTS.md
+
+## Setup commands
+- Install deps: `pnpm install`
+- Run tests: `pnpm test`
+
+## Code style
+- TypeScript strict mode, single quotes, no semicolons.
+EOF
+    run bash "$SCRIPT" "$TMPDIR"
+    assert_success
+    assert_output --partial "INFO"
+    assert_output --partial "security"
+}
+
+@test "suggests trimming a nested AGENTS.md that duplicates the root file" {
+    mkdir -p "$TMPDIR/packages/api"
+    cat > "$TMPDIR/AGENTS.md" <<'EOF'
+# AGENTS.md
+
+## Setup commands
+- Install deps: `pnpm install`
+- Run tests: `pnpm test`
+- Lint: `pnpm lint`
+- Build: `pnpm build`
+EOF
+    cat > "$TMPDIR/packages/api/AGENTS.md" <<'EOF'
+# AGENTS.md
+
+## Setup commands
+- Install deps: `pnpm install`
+- Run tests: `pnpm test`
+- Lint: `pnpm lint`
+- Build: `pnpm build`
+EOF
+    run bash "$SCRIPT" "$TMPDIR"
+    assert_success
+    assert_output --partial "SUGGESTION"
+    assert_output --partial "packages/api/AGENTS.md"
+}