feat(ST-702): vendor Scrum4Me schema via submodule + sync script

- Add vendor/scrum4me as a git submodule (read-only source of truth)
- scripts/sync-schema.sh copies schema.prisma into prisma/, stripping
  the upstream prisma-erd-generator block we don't ship
- Track the synced schema in git so a fresh clone works after
  'git submodule update --init && npm install'
- postinstall runs 'prisma generate' so @prisma/client is ready

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

scripts/sync-schema.sh

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+# Sync prisma/schema.prisma from the vendored Scrum4Me submodule.
+#
+# Strips the `generator erd` block — that generator depends on
+# prisma-erd-generator which we don't ship in this MCP package. The
+# schema is otherwise byte-identical with upstream.
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "$0")/.." && pwd)"
+SRC="$ROOT/vendor/scrum4me/prisma/schema.prisma"
+DST="$ROOT/prisma/schema.prisma"
+
+if [ ! -f "$SRC" ]; then
+  echo "error: $SRC not found — run 'git submodule update --init' first" >&2
+  exit 1
+fi
+
+mkdir -p "$ROOT/prisma"
+
+# Strip the `generator erd { ... }` block (multi-line, balanced braces).
+awk '
+  /^generator erd \{/ { skip = 1; next }
+  skip && /^\}/ { skip = 0; next }
+  skip { next }
+  { print }
+' "$SRC" > "$DST"
+
+echo "synced schema from $(cd "$ROOT/vendor/scrum4me" && git rev-parse --short HEAD) to prisma/schema.prisma"