feat(8.0)!: flip requireSubtype default to true (BRAINY-8.0-SUBTYPE-CONTRACT § C-1)

Brainy 8.0 makes subtype required by default on every public write path
(`add`, `addMany`, `update`, `relate`, `relateMany`, `updateRelation`,
import). Per the locked C-1 contract, every entity and relation gets a
non-empty subtype string by the time the storage layer sees it.

OPT-OUT REMAINS FULLY SUPPORTED

The runtime flag is still consumer-controlled. Three opt-out paths
cover migration / legacy fixtures / typed escape:

- `new Brainy({ requireSubtype: false })` — last-resort: turn off the
  contract entirely. Recommended only for migration windows or test
  fixtures that legitimately can't supply a subtype.
- `new Brainy({ requireSubtype: { except: [NounType.Thing, ...] } })` —
  per-type allowlist: strict everywhere except the listed types.
- `brain.requireSubtype(type, options)` — per-type registration with
  optional vocabulary. Composes with the brain-wide flag.

Default is now `true`. Opt-out is explicit and documented; nothing
silently degrades.

TEST SWEEP

Bulk-applied `requireSubtype: false` to every `new Brainy({...})` call
site across 120 test files. Three sed patterns covered the shapes:
  - `new Brainy({` → `new Brainy({ requireSubtype: false,`
  - `new Brainy<T>({` → `new Brainy<T>({ requireSubtype: false,`
  - `new Brainy()` → `new Brainy({ requireSubtype: false })`

tests/helpers/test-factory.ts → createTestConfig() defaults
`requireSubtype: false` so test files using the helper inherit the
opt-out without per-site edits.

The test sites that DO exercise subtype semantics (the
subtype-and-facets suite, the strict-mode-self-test suite, the verb-
subtype-and-enforcement suite, etc.) already pass real subtypes — they
were the 7.30.x acceptance tests for this contract. Those tests
continue to pass unchanged.

CHANGES

src/brainy.ts
- normalizeConfig() — `requireSubtype` default `false` → `true`.
  Comment refreshed to document the three opt-out paths.

tests/* (120 files)
- Bulk-edited brain construction sites. No functional test changes; the
  opt-out preserves the test author's original intent.

tests/helpers/test-factory.ts
- createTestConfig() base config gains `requireSubtype: false`.

NO-OP for consumers who were already passing subtype on every write.

For consumers who weren't, the upgrade path is one of the three opt-out
forms above. Migration recipe documented in 8.0 release notes (next
commit).

VERIFICATION

- npx tsc --noEmit: clean
- npm test: 1408 / 1409 (same pre-existing race-condition outstanding;
  no other regressions from the flip)

tests/comprehensive/core-api.test.ts

@@ -11,7 +11,7 @@ describe('Brainy v3.0 Core API Tests', () => {
   let brain: Brainy
 
   beforeEach(async () => {
-    brain = new Brainy({
+    brain = new Brainy({ requireSubtype: false,
       storage: { type: 'memory' }
     })
     await brain.init()

tests/comprehensive/find-triple-intelligence.test.ts

@@ -12,7 +12,7 @@ describe('Find and Triple Intelligence', () => {
   let testData: any[]
 
   beforeAll(async () => {
-    brain = new Brainy({
+    brain = new Brainy({ requireSubtype: false,
       storage: { type: 'memory' }
     })
     await brain.init()

tests/comprehensive/public-api-complete.test.ts

@@ -33,7 +33,7 @@ describe('Brainy Public API - Complete Coverage', () => {
 
   describe('Core CRUD Operations', () => {
     beforeEach(async () => {
-      brain = new Brainy({ storage: { type: 'memory' } })
+      brain = new Brainy({ requireSubtype: false, storage: { type: 'memory' } })
       await brain.init()
     })
 
@@ -236,7 +236,7 @@ describe('Brainy Public API - Complete Coverage', () => {
 
   describe('Relationship Operations', () => {
     beforeEach(async () => {
-      brain = new Brainy({ storage: { type: 'memory' } })
+      brain = new Brainy({ requireSubtype: false, storage: { type: 'memory' } })
       await brain.init()
     })
 
@@ -419,7 +419,7 @@ describe('Brainy Public API - Complete Coverage', () => {
 
   describe('Search Operations', () => {
     beforeEach(async () => {
-      brain = new Brainy({ storage: { type: 'memory' } })
+      brain = new Brainy({ requireSubtype: false, storage: { type: 'memory' } })
       await brain.init()
 
       await brain.addMany({
@@ -533,7 +533,7 @@ describe('Brainy Public API - Complete Coverage', () => {
     let entityIds: string[]
 
     beforeEach(async () => {
-      brain = new Brainy({ storage: { type: 'memory' } })
+      brain = new Brainy({ requireSubtype: false, storage: { type: 'memory' } })
       await brain.init()
 
       const result = await brain.addMany({
@@ -627,7 +627,7 @@ describe('Brainy Public API - Complete Coverage', () => {
 
   describe('Statistics', () => {
     beforeEach(async () => {
-      brain = new Brainy({ storage: { type: 'memory' } })
+      brain = new Brainy({ requireSubtype: false, storage: { type: 'memory' } })
       await brain.init()
     })
 
@@ -661,7 +661,7 @@ describe('Brainy Public API - Complete Coverage', () => {
       const fsTestDir = path.join(tmpdir(), `brainy-fs-crud-${Date.now()}`)
       await fs.mkdir(fsTestDir, { recursive: true })
 
-      const fsBrain = new Brainy({
+      const fsBrain = new Brainy({ requireSubtype: false,
         storage: {
           type: 'filesystem',
           options: { path: fsTestDir }
@@ -695,7 +695,7 @@ describe('Brainy Public API - Complete Coverage', () => {
       const fsTestDir = path.join(tmpdir(), `brainy-fs-concurrent-${Date.now()}`)
       await fs.mkdir(fsTestDir, { recursive: true })
 
-      const fsBrain = new Brainy({
+      const fsBrain = new Brainy({ requireSubtype: false,
         storage: {
           type: 'filesystem',
           options: { path: fsTestDir }
@@ -723,7 +723,7 @@ describe('Brainy Public API - Complete Coverage', () => {
 
   describe('Error Recovery and Resilience', () => {
     beforeEach(async () => {
-      brain = new Brainy({ storage: { type: 'memory' } })
+      brain = new Brainy({ requireSubtype: false, storage: { type: 'memory' } })
       await brain.init()
     })
 
@@ -780,7 +780,7 @@ describe('Brainy Public API - Complete Coverage', () => {
 
   describe('Performance', () => {
     it('should handle moderate-scale operations', async () => {
-      const perfBrain = new Brainy({ storage: { type: 'memory' } })
+      const perfBrain = new Brainy({ requireSubtype: false, storage: { type: 'memory' } })
       await perfBrain.init()
 
       // Add 50 items in batches
@@ -806,7 +806,7 @@ describe('Brainy Public API - Complete Coverage', () => {
 
   describe('Clear Operations', () => {
     beforeEach(async () => {
-      brain = new Brainy({ storage: { type: 'memory' } })
+      brain = new Brainy({ requireSubtype: false, storage: { type: 'memory' } })
       await brain.init()
 
       await brain.addMany({