test: add run-tests.sh, fix stale tests for marketplace model

- Add tests/run-tests.sh: discovers and runs all test-*.sh (including
  plugin subdirs) and the bats suite; replaces per-script pre-push calls
- Add tests/run-tests.bats: TDD coverage for run-tests.sh behaviours
- Update setup-hooks.sh: pre-push block now calls run-tests.sh
- Fix test-install.sh: remove provider adapter symlink tests (adapter
  removed in marketplace migration), guard skills loops on dir existence
- Fix test-instructions-and-docs.sh: content index checks now point to
  core/AGENTS.md (where it lives), remove ard/bug dir assertions
- Fix test-setup-hooks.sh: assert pre-push hook calls run-tests.sh

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

tests/run-tests.sh

@@ -0,0 +1,57 @@
+#!/usr/bin/env bash
+# Run all test-*.sh files in the repo (including plugins) and the bats suite.
+# Usage: bash tests/run-tests.sh [--bats-only]
+#
+# TEST_DIR — override root to search for test-*.sh (default: REPO_ROOT); used by tests.
+set -euo pipefail
+
+REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+BATS="$REPO_ROOT/tests/run-bats.sh"
+BATS_ONLY=false
+[[ "${1:-}" == "--bats-only" ]] && BATS_ONLY=true
+
+SEARCH_ROOT="${TEST_DIR:-$REPO_ROOT}"
+
+FAILED=()
+PASSED=0
+
+run_bats() {
+  if [[ -x "$BATS" ]]; then
+    echo "=== bats ==="
+    bash "$BATS"
+    echo ""
+  fi
+}
+
+if $BATS_ONLY; then
+  run_bats
+  exit 0
+fi
+
+run_bats
+
+mapfile -t SCRIPTS < <(
+  find "$SEARCH_ROOT" -name "test-*.sh" \
+    -not -path "*/.git/*" \
+    | sort
+)
+
+for script in "${SCRIPTS[@]}"; do
+  rel="${script#"$SEARCH_ROOT/"}"
+  echo "=== $rel ==="
+  if bash "$script"; then
+    PASSED=$((PASSED + 1))
+  else
+    FAILED+=("$rel")
+  fi
+  echo ""
+done
+
+echo "=== Summary: $PASSED passed, ${#FAILED[@]} failed ==="
+if [[ ${#FAILED[@]} -gt 0 ]]; then
+  echo "Failed scripts:"
+  for s in "${FAILED[@]}"; do
+    echo "  $s"
+  done
+  exit 1
+fi