feat: verb subtype + updateRelation + requireSubtype enforcement

Brings verbs to first-class parity with nouns. The 7.29.0 subtype primitive
shipped for entities only; this release ships the symmetric verb mirror plus
the enforcement layer for ensuring every entity AND every relationship has
both type AND subtype.

Layer V1 — verb subtype mirror
- HNSWVerbWithMetadata.subtype + STANDARD_VERB_FIELDS set + resolveVerbField()
- Relation<T>.subtype, RelateParams<T>.subtype, UpdateRelationParams<T> extended,
  GetRelationsParams.subtype, GraphConstraints.subtype (for find connected)
- relate() persists subtype on verbMetadata + GraphVerb + transaction ops
- getRelations({ type, subtype }) fast-path filter with set membership
- find({ connected: { via, subtype, depth } }) traversal filter (depth-1 on
  the JS path; explicit error on depth > 1 pointing at Cortex native)
- verbsToRelations + storage destructure sites surface subtype to top-level
- All three graph-index fast-path queries (getVerbsBySource/ByTarget) enrich
  with subtype from metadata

Layer V2 — updateRelation() closes a pre-7.30 gap
- New first-class verb update method (parallel to update() for nouns)
- Changes subtype/type/weight/confidence/data/metadata in place
- Re-indexes in graph adjacency when verb type changes; id preserved
- validateUpdateRelationParams enforces id + at-least-one-field-to-update

Layer V3 — verb subtype storage rollup
- verbSubtypeCountsByType: Map<number, Map<string, number>> on BaseStorage
- verbSubtypeByIdCache for self-heal during update/delete
- incrementVerbSubtypeCount + decrementVerbSubtypeCount maintain state
- loadVerbSubtypeStatistics + saveVerbSubtypeStatistics persist to
  _system/verb-subtype-statistics.json (mirrors noun-side shape)
- rebuildVerbSubtypeCounts for poison recovery / explicit repair
- getVerbSubtypeCountsByType accessor for the public counts API
- Wired into init() / flushCounts() / saveVerbMetadata / deleteVerbMetadata

Layer V4 — verb counts API + relationshipSubtypesOf
- brain.counts.byRelationshipSubtype(verb, subtype?) — O(1) breakdown or point
- brain.counts.topRelationshipSubtypes(verb, n) — top N by count
- brain.relationshipSubtypesOf(verb) — sorted distinct subtypes

Layer V5 — migrateField extended to verbs
- New entityKind?: 'noun' | 'verb' | 'both' option (default 'noun')
- Mirror verb iteration via storage.getVerbs() with same path semantics
- verbToRelationLike + buildRelationMigrationUpdate helpers project the
  storage verb shape onto the Entity<T>-shaped surface readPath understands
- Routes through new updateRelation() for the verb-side rewrite

Enforcement (opt-in in 7.30, default in 8.0)
- brain.requireSubtype(type, options) — unified API for NounType OR VerbType.
  Registers per-type rules with optional values whitelist; composes with the
  brain-wide flag.
- new Brainy({ requireSubtype: true }) — brain-wide strict mode. Every public
  write path validates the pairing guarantee.
- { except: [NounType.Thing, ...] } form for catch-all type exemptions
- Atomic-fail semantics on addMany / relateMany — pre-validate every item
  before any storage write, throw on first failure with item index
- Per-type rules + brain-wide flag both throw with descriptive messages
- VFS infrastructure bypass via metadata.isVFSEntity / isVFS markers so
  brain's own VFS writes don't get rejected when strict mode is on

VFS labeling — concrete subtypes for infrastructure entities
- VFS root: NounType.Collection + subtype: 'vfs-root' (was bare Collection)
- VFS directories: subtype: 'vfs-directory'
- VFS files: subtype: 'vfs-file' (NounType still mime-based)
- VFS containment edges: VerbType.Contains + subtype: 'vfs-contains'
- Lets consumers cleanly enumerate VFS state via find({ subtype: 'vfs-file' })
  and distinguish Brainy's VFS Collections from user-created Collections

Docs
- docs/guides/subtypes-and-facets.md extended with Layer V (Verbs) section +
  Enforcement section. New full reference at the bottom split into Layer 1
  (nouns), Layer V (verbs), Layer 2 (facets), Layer 3 (migration), Enforcement.
- docs/api/README.md adds updateRelation(), getRelations({ subtype }), the
  three verb-side counts methods, requireSubtype(), and the brain-wide
  constructor option. relate() params include subtype.
- docs/DATA_MODEL.md adds a Subtype-for-VerbType section + STANDARD_VERB_FIELDS
- docs/architecture/finite-type-system.md extends Principle 1a to verbs
- docs/QUERY_OPERATORS.md adds a verb-subtype filter section covering
  getRelations and find({connected, subtype}) traversal
- README.md "Subtypes" section now shows both noun + verb in one example +
  the enforcement APIs
- RELEASES.md v7.30.0 entry with the full noun/verb capability parity matrix

Tests
- tests/integration/verb-subtype-and-enforcement.test.ts — 30 new tests
  covering V1 round-trips, V1 set membership, updateRelation in place,
  updateRelation preservation, V2 counts breakdown + point + topN + distinct,
  V2 decrements on unrelate, V2 re-routes on updateRelation, V3 depth-1
  traversal filter, V3 depth>1 explicit error, V4 verb migration, V4 both
  entity kinds, V4 readBoth preservation, V5 per-type required rejection,
  V5 vocabulary rejection, V5 on-vocab acceptance, V5 verb-side enforcement,
  V5 addMany atomic-fail, V5 relateMany atomic-fail, V5 update enforcement,
  V5 updateRelation enforcement, V5 brain-wide strict mode, V5 except clause.

Verification
- Unit suite: 1468/1468 passing
- Noun subtype integration (7.29 carryover): 26/26 passing
- Verb subtype + enforcement integration: 30/30 passing
- Type-check: clean
- Build: clean
- Public closed-source reference audit: clean

Internal 8.0 spec
- .strategy/BRAINY-8.0-SUBTYPE-CONTRACT.md (gitignored, not in npm artifact)
  documents the contract upgrade Cortex 3.0 implements against: required-by-
  default subtype, SubtypeRegistry typing hook, native simplification,
  multi-hop traversal native fast path, brain.fillSubtypes() migration helper.
  Coordinated via PLATFORM-HANDOFF rows CTX-SUBTYPE-PARITY-V2 (7.30 parallel
  work) and CTX-SUBTYPE-8.0-CONTRACT (8.0 spec).

src/utils/paramValidation.ts

@@ -5,7 +5,7 @@
  * Only enforces universal truths, learns everything else
  */
 
-import { FindParams, AddParams, UpdateParams, RelateParams } from '../types/brainy.types.js'
+import { FindParams, AddParams, UpdateParams, RelateParams, UpdateRelationParams } from '../types/brainy.types.js'
 import { NounType, VerbType } from '../types/graphTypes.js'
 
 // Dynamic import for Node.js os and fs modules
@@ -407,7 +407,7 @@ export function validateRelateParams(params: RelateParams): void {
   if (!params.from) {
     throw new Error('from entity ID is required')
   }
-  
+
   if (!params.to) {
     throw new Error('to entity ID is required')
   }
@@ -421,7 +421,7 @@ export function validateRelateParams(params: RelateParams): void {
   } else if (!Object.values(VerbType).includes(params.type)) {
     throw new Error(`invalid VerbType: ${params.type}`)
   }
-  
+
   // Universal truth: weight must be 0-1
   if (params.weight !== undefined) {
     if (params.weight < 0 || params.weight > 1) {
@@ -430,6 +430,40 @@ export function validateRelateParams(params: RelateParams): void {
   }
 }
 
+/**
+ * Validate UpdateRelationParams. Mirror of validateUpdateParams for verbs —
+ * requires id + at least one field to change; bounds-checks weight/confidence;
+ * accepts type/subtype/weight/confidence/data/metadata changes.
+ */
+export function validateUpdateRelationParams(params: UpdateRelationParams): void {
+  if (!params.id) {
+    throw new Error('id is required for updateRelation')
+  }
+
+  if (
+    !params.data &&
+    !params.metadata &&
+    !params.type &&
+    params.subtype === undefined &&
+    params.weight === undefined &&
+    params.confidence === undefined
+  ) {
+    throw new Error('updateRelation: must specify at least one field to update')
+  }
+
+  if (params.type !== undefined && !Object.values(VerbType).includes(params.type)) {
+    throw new Error(`invalid VerbType: ${params.type}`)
+  }
+
+  if (params.weight !== undefined && (params.weight < 0 || params.weight > 1)) {
+    throw new Error('weight must be between 0 and 1')
+  }
+
+  if (params.confidence !== undefined && (params.confidence < 0 || params.confidence > 1)) {
+    throw new Error('confidence must be between 0 and 1')
+  }
+}
+
 /**
  * Get current validation configuration
  * Useful for debugging and monitoring