feat: add marketplace-architect skill with Bash scripts and evals

Adds a new skill for creating, managing, and adopting plugins across
Claude Code and GitHub Copilot CLI marketplaces. Includes three Bash
scripts (inventory, gen_manifests, validate), three reference docs
(cross-compat, claude-code, copilot-cli), a test harness with 18
passing tests, and an eval.yaml. Also adds the `marketplace` category
to CATEGORIES.md and commits the plugin marketplace architecture
research doc that informed the skill design.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.agents/skills/marketplace-architect/scripts/inventory.sh

@@ -0,0 +1,121 @@
+#!/usr/bin/env bash
+# Scan a repository and classify every asset as skill/command/agent/hook/prompt/MCP.
+# Outputs a markdown table of findings plus a list of cross-reference warnings.
+#
+# Usage: inventory.sh <repo-path>
+
+set -euo pipefail
+
+if [[ $# -lt 1 ]]; then
+  echo "Usage: inventory.sh <repo-path>" >&2
+  exit 1
+fi
+
+ROOT="$(cd "$1" && pwd)"
+
+if [[ ! -d "$ROOT" ]]; then
+  echo "Error: $ROOT is not a directory" >&2
+  exit 1
+fi
+
+# ── classify assets ──────────────────────────────────────────────────────────
+
+declare -a ROWS=()
+declare -a CROSS_REFS=()
+
+while IFS= read -r -d '' path; do
+  rel="${path#"$ROOT/"}"
+  name="$(basename "$path")"
+  dir="$(dirname "$rel")"
+  parent="$(basename "$dir")"
+
+  # Skip hidden dirs except .claude-plugin and .github
+  skip=false
+  IFS='/' read -ra parts <<< "$dir"
+  for part in "${parts[@]}"; do
+    if [[ "$part" == .* && "$part" != ".claude-plugin" && "$part" != ".github" ]]; then
+      skip=true; break
+    fi
+  done
+  $skip && continue
+
+  asset_type=""
+
+  case "$name" in
+    SKILL.md)             asset_type="skill" ;;
+    hooks.json)           asset_type="hook" ;;
+    .mcp.json)            asset_type="mcp" ;;
+    .lsp.json)            asset_type="lsp" ;;
+    plugin.json)          asset_type="manifest-plugin" ;;
+    marketplace.json)     asset_type="manifest-marketplace" ;;
+    *.agent.md)           asset_type="agent-copilot" ;;
+    *.md)
+      if [[ "$parent" == "agents" ]]; then
+        asset_type="agent-claude"
+      elif [[ "$parent" == "commands" ]]; then
+        asset_type="command"
+      elif [[ "$rel" != *"/skills/"* && "$rel" != *"/commands/"* && "$rel" != *"/agents/"* ]]; then
+        asset_type="prompt"
+      fi
+      ;;
+  esac
+
+  [[ -n "$asset_type" ]] && ROWS+=("$asset_type|$rel")
+
+  # Check for cross-references in text files
+  case "$name" in *.md|*.json|*.sh)
+    if grep -q '\.\.\/' "$path" 2>/dev/null; then
+      while IFS= read -r line; do
+        lineno="${line%%:*}"
+        content="${line#*:}"
+        CROSS_REFS+=("$rel:$lineno: $content")
+      done < <(grep -n '\.\.\/' "$path" 2>/dev/null | head -20)
+    fi
+    ;;
+  esac
+
+done < <(find "$ROOT" -type f -print0 | sort -z)
+
+# ── report ───────────────────────────────────────────────────────────────────
+
+echo "# Asset Inventory: $ROOT"
+echo ""
+echo "## Assets"
+echo ""
+echo "| Type | Path |"
+echo "|---|---|"
+for row in "${ROWS[@]+"${ROWS[@]}"}"; do
+  type="${row%%|*}"
+  path="${row#*|}"
+  echo "| \`$type\` | \`$path\` |"
+done | sort
+
+total="${#ROWS[@]}"
+echo ""
+echo "**Total: $total assets**"
+echo ""
+
+# Summary by type
+echo "## Summary by type"
+echo ""
+for row in "${ROWS[@]+"${ROWS[@]}"}"; do
+  echo "${row%%|*}"
+done | sort | uniq -c | while read -r count type; do
+  echo "- \`$type\`: $count"
+done
+
+# Cross-reference warnings
+echo ""
+if [[ ${#CROSS_REFS[@]} -gt 0 ]]; then
+  echo "## ⚠️ Cross-reference warnings (${#CROSS_REFS[@]} found)"
+  echo ""
+  echo "These \`../\` references will break after install-time caching:"
+  echo ""
+  for ref in "${CROSS_REFS[@]}"; do
+    echo "- \`$ref\`"
+  done
+else
+  echo "## Cross-references"
+  echo ""
+  echo "No \`../\` cross-references found. Safe to proceed with plugin boundaries."
+fi