fix(nodb): set cmdCtx.StoreActive in initializeNoDbMode (GH#897)

The bug: initializeNoDbMode() was setting the legacy global storeActive
but not cmdCtx.StoreActive. When ensureStoreActive() checked
isStoreActive(), it used cmdCtx.StoreActive (which was false), causing
the JSONL-only mode error even when --no-db was passed.

The fix: Use accessor functions (lockStore, setStore, setStoreActive,
unlockStore) which set both the legacy globals and cmdCtx fields.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

cmd/bd/nodb.go

@@ -73,10 +73,11 @@ func initializeNoDbMode() error {
 	debug.Logf("using prefix '%s'", prefix)
 
 	// Set global store and mark as active (fixes bd comment --no-db)
-	storeMutex.Lock()
-	store = memStore
-	storeActive = true
-	storeMutex.Unlock()
+	// GH#897: Use accessor functions to also set cmdCtx fields, not just globals
+	lockStore()
+	setStore(memStore)
+	setStoreActive(true)
+	unlockStore()
 	return nil
 }