fix: add rootDirectory to BrainyConfig.storage type

The storage config type only exposed { type, options, branch } but plugin
storage factories (e.g. Cortex mmap) read rootDirectory from the top level
of the config object. This caused undefined storage paths when Cortex was
active. The underlying StorageOptions interface already declares
rootDirectory — this aligns BrainyConfig.storage to match.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@soulcraft/brainy",
-  "version": "7.19.10",
+  "version": "7.19.11",
   "description": "Universal Knowledge Protocol™ - World's first Triple Intelligence database unifying vector, graph, and document search in one API. Stage 3 CANONICAL: 42 nouns × 127 verbs covering 96-97% of all human knowledge.",
   "main": "dist/index.js",
   "module": "dist/index.js",

src/types/brainy.types.ts

@@ -889,6 +889,9 @@ export interface BrainyConfig {
   // Storage configuration
   storage?: {
     type: 'auto' | 'memory' | 'filesystem' | 's3' | 'r2' | 'opfs' | 'gcs'
+    /** Root directory for filesystem storage. Passed through to storage factories
+     *  including plugin-provided factories (e.g. Cortex mmap). */
+    rootDirectory?: string
     options?: any
     branch?: string              // COW branch name (default: 'main')
   }