fix(storage): neutral queryConstraints honored by both adapters

Bug: server adapter accepted queryConstraints (orderBy/limit) but ignored them.
Combat log [orderBy('timestamp','desc'), limit(500)] returned ALL logs unordered
in server mode — unbounded growth. No test caught it: shared contract tested
subscribeCollection with 0 constraints; the firebase-only queryConstraint test
never touched the server adapter. Parity gap.

Fix (Plan A — neutral shape):
- index.js: orderBy()/limit() now NEUTRAL builders returning {__type}. Removed
  SDK orderBy/limit re-export.
- firebase.js: subscribeCollection translates neutral -> SDK query constraints.
- server.js: applyConstraints() helper sorts/limits client-side (backend returns
  all). Constraints stored per collection, applied on initial fetch + WS change.
- contract.js: added 3 queryConstraint tests (orderBy desc, limit, no-constraints)
  to SHARED contract — both adapters now run identical assertions.
- firebase.contract.test.js: removed now-redundant firebase-only constraint
  block (covered by shared contract).

Data impact: ZERO. Constraints are query-time only, never stored. Combat log
docs keep timestamp field. No Firebase data migration needed.

208 tests green.

src/storage/index.js

@@ -1,5 +1,6 @@
 // src/storage/index.js — storage factory + SDK re-exports.
 // STORAGE=firebase (default): adapter wraps SDK. STORAGE=server: backend.
+// orderBy/limit below = NEUTRAL builders (not SDK passthrough).
 // App.js imports getStorage() for subscribe; still imports SDK pieces for writes (per-group refactor pending).
 
 import { initializeApp } from 'firebase/app';
@@ -8,7 +9,7 @@ import {
 } from 'firebase/auth';
 import {
   getFirestore, doc, setDoc, getDoc, getDocs, addDoc, collection,
-  onSnapshot, updateDoc, deleteDoc, query, orderBy, limit, writeBatch,
+  onSnapshot, updateDoc, deleteDoc, query, writeBatch,
 } from 'firebase/firestore';
 import { initFirebase, createFirebaseStorage } from './firebase';
 import { createServerStorage } from './server';
@@ -38,9 +39,16 @@ export function getStorageMode() {
   return process.env.REACT_APP_STORAGE || 'firebase';
 }
 
+// Neutral query-constraint builders. App builds constraints with these (not
+// raw SDK), so both adapters read the same shape. firebase adapter translates
+// neutral -> SDK; server adapter applies client-side. Combat log uses these:
+//   [orderBy('timestamp','desc'), limit(500)]
+export function orderBy(field, dir) { return { __type: 'orderBy', field, dir }; }
+export function limit(n) { return { __type: 'limit', n }; }
+
 export {
   initializeApp,
   getAuth, signInAnonymously, onAuthStateChanged, signInWithCustomToken,
   getFirestore, doc, setDoc, getDoc, getDocs, addDoc, collection,
-  onSnapshot, updateDoc, deleteDoc, query, orderBy, limit, writeBatch,
+  onSnapshot, updateDoc, deleteDoc, query, writeBatch,
 };