chore: add Claude Project Knowledge sync tooling

- scripts/sync-claude-docs.sh with sync/check/list/help subcommands
- scripts/install-claude-sync-hooks.sh for one-time hook setup
- .githooks/post-commit auto-syncs on dev-doc changes
- .githooks/pre-push warns (non-blocking) on stale sync
- .claude-sync.conf lists 11 synced documents
- SYNC_MANIFEST.md provides drift-detection anchor for Claude Chat
- package.json: npm run sync:docs | sync:check
- .gitignore excludes .claude-sync/ output directory

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.githooks/pre-push

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+
+# Warn (non-blocking) if .claude-sync/ is stale relative to current source files.
+
+REPO_ROOT="$(git rev-parse --show-toplevel 2>/dev/null || true)"
+if [ -z "${REPO_ROOT}" ]; then
+  exit 0
+fi
+cd "${REPO_ROOT}"
+
+SYNC_SCRIPT="scripts/sync-claude-docs.sh"
+if [ ! -f "${SYNC_SCRIPT}" ]; then
+  exit 0
+fi
+
+set +e
+bash "${SYNC_SCRIPT}" check >/dev/null 2>&1
+rc=$?
+set -e
+
+if [ "${rc}" -ne 0 ]; then
+  {
+    printf '%s\n' "⚠️  .claude-sync/ is stale relative to current dev-docs."
+    printf '%s\n' "    Fix: bash scripts/sync-claude-docs.sh sync"
+    printf '%s\n' "    (push is NOT blocked)"
+  } >&2
+fi
+
+exit 0