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/post-commit

@@ -0,0 +1,54 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Auto-sync Claude Project Knowledge when a commit touched any configured doc.
+
+REPO_ROOT="$(git rev-parse --show-toplevel 2>/dev/null || true)"
+if [ -z "${REPO_ROOT}" ]; then
+  exit 0
+fi
+cd "${REPO_ROOT}"
+
+CONF_FILE=".claude-sync.conf"
+SYNC_SCRIPT="scripts/sync-claude-docs.sh"
+
+if [ ! -f "${CONF_FILE}" ] || [ ! -f "${SYNC_SCRIPT}" ]; then
+  exit 0
+fi
+
+# Files changed in the commit we just made.
+changed="$(git diff-tree --no-commit-id --name-only -r HEAD 2>/dev/null || true)"
+if [ -z "${changed}" ]; then
+  exit 0
+fi
+
+# Configured paths (strip # comments and blanks).
+configured="$(awk '
+  {
+    sub(/#.*/, "")
+    gsub(/^[[:space:]]+|[[:space:]]+$/, "")
+    if (length($0) > 0) print
+  }
+' "${CONF_FILE}")"
+
+match=0
+while IFS= read -r cfile; do
+  [ -z "${cfile}" ] && continue
+  while IFS= read -r conf_path; do
+    [ -z "${conf_path}" ] && continue
+    if [ "${cfile}" = "${conf_path}" ]; then
+      match=1
+      break 2
+    fi
+  done <<EOF
+${configured}
+EOF
+done <<EOF
+${changed}
+EOF
+
+if [ "${match}" -eq 1 ]; then
+  bash "${SYNC_SCRIPT}" sync
+fi
+
+exit 0