fix: exclude __words__ keyword index from corruption detection and getStats()

The __words__ keyword index stores 50-5000 entries per entity (one per
word), which inflated avg entries/entity well above the corruption
threshold of 100. This caused:

1. validateConsistency() to falsely detect corruption on every startup,
   triggering unnecessary clearAllIndexData() + rebuild() cycles
2. getStats() to log false "Metadata index may be corrupted" warnings
   and report inflated totalEntries/totalIds stats

Both methods now skip __words__ when counting, so stats and health
checks reflect metadata fields only (noun, type, createdAt, etc.).
Keyword search is unaffected since the __words__ field index itself
is not modified.

src/vfs/semantic/SemanticPathResolver.ts

@@ -317,7 +317,7 @@ export class SemanticPathResolver {
   }
 
   /**
-   * Invalidate ALL caches (v6.3.0)
+   * Invalidate ALL caches
    * Clears both traditional path cache AND semantic cache
    * Call this when switching branches, clearing data, or forking
    */

src/vfs/semantic/projections/AuthorProjection.ts

@@ -52,7 +52,7 @@ export class AuthorProjection extends BaseProjectionStrategy {
    * Resolve author to entity IDs using REAL Brainy.find()
    */
   async resolve(brain: Brainy, vfs: VirtualFileSystem, authorName: string): Promise<string[]> {
-    // v4.7.0: VFS entities are part of the knowledge graph
+    // VFS entities are part of the knowledge graph
     const results = await brain.find({
       where: {
         vfsType: 'file',

src/vfs/semantic/projections/TagProjection.ts

@@ -52,7 +52,7 @@ export class TagProjection extends BaseProjectionStrategy {
    * Resolve tag to entity IDs using REAL Brainy.find()
    */
   async resolve(brain: Brainy, vfs: VirtualFileSystem, tagName: string): Promise<string[]> {
-    // v4.7.0: VFS entities are part of the knowledge graph
+    // VFS entities are part of the knowledge graph
     const results = await brain.find({
       where: {
         vfsType: 'file',

src/vfs/semantic/projections/TemporalProjection.ts

@@ -69,7 +69,7 @@ export class TemporalProjection extends BaseProjectionStrategy {
     const endOfDay = new Date(date)
     endOfDay.setHours(23, 59, 59, 999)
 
-    // v4.7.0: VFS entities are part of the knowledge graph
+    // VFS entities are part of the knowledge graph
     const results = await brain.find({
       where: {
         vfsType: 'file',