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/integration/clear-persistence.test.ts

@@ -35,7 +35,7 @@ describe('Clear Persistence Bug Fix (v5.10.4)', () => {
 
   it('should fully clear persistent storage (the reported scenario)', async () => {
     // Step 1: Create and populate instance
-    const brain1 = new Brainy({
+    const brain1 = new Brainy({ requireSubtype: false,
       storage: {
         type: 'filesystem',
         path: testStoragePath,
@@ -59,7 +59,7 @@ describe('Clear Persistence Bug Fix (v5.10.4)', () => {
     expect(entityCount2).toBe(0)
 
     // Step 3: Create NEW instance (simulate server restart)
-    const brain2 = new Brainy({
+    const brain2 = new Brainy({ requireSubtype: false,
       storage: {
         type: 'filesystem',
         path: testStoragePath,
@@ -75,7 +75,7 @@ describe('Clear Persistence Bug Fix (v5.10.4)', () => {
   })
 
   it('should create cow-disabled marker file', async () => {
-    const brain = new Brainy({
+    const brain = new Brainy({ requireSubtype: false,
       storage: {
         type: 'filesystem',
         path: testStoragePath
@@ -96,7 +96,7 @@ describe('Clear Persistence Bug Fix (v5.10.4)', () => {
   })
 
   it('should delete _cow/ directory', async () => {
-    const brain = new Brainy({
+    const brain = new Brainy({ requireSubtype: false,
       storage: {
         type: 'filesystem',
         path: testStoragePath
@@ -122,7 +122,7 @@ describe('Clear Persistence Bug Fix (v5.10.4)', () => {
 
   it('should prevent COW reinitialization after clear()', async () => {
     // Create and clear
-    const brain1 = new Brainy({
+    const brain1 = new Brainy({ requireSubtype: false,
       storage: { type: 'filesystem', path: testStoragePath }
     })
     await brain1.init()
@@ -130,7 +130,7 @@ describe('Clear Persistence Bug Fix (v5.10.4)', () => {
     await brain1.clear()
 
     // Create new instance
-    const brain2 = new Brainy({
+    const brain2 = new Brainy({ requireSubtype: false,
       storage: { type: 'filesystem', path: testStoragePath }
     })
     await brain2.init()
@@ -150,14 +150,14 @@ describe('Clear Persistence Bug Fix (v5.10.4)', () => {
 
     try {
       // Iteration 1
-      const brain1 = new Brainy({ storage: { type: 'filesystem', path: storagePath }})
+      const brain1 = new Brainy({ requireSubtype: false, storage: { type: 'filesystem', path: storagePath }})
       await brain1.init()
       await brain1.add({ data:'Entity 1', type: 'concept' })
       expect((await brain1.find({ type: 'concept' })).length).toBe(1)
       await brain1.clear()
 
       // Iteration 2
-      const brain2 = new Brainy({ storage: { type: 'filesystem', path: storagePath }})
+      const brain2 = new Brainy({ requireSubtype: false, storage: { type: 'filesystem', path: storagePath }})
       await brain2.init()
       expect((await brain2.find({ type: 'concept' })).length).toBe(0)
       await brain2.add({ data:'Entity 2', type: 'concept' })
@@ -165,7 +165,7 @@ describe('Clear Persistence Bug Fix (v5.10.4)', () => {
       await brain2.clear()
 
       // Iteration 3
-      const brain3 = new Brainy({ storage: { type: 'filesystem', path: storagePath }})
+      const brain3 = new Brainy({ requireSubtype: false, storage: { type: 'filesystem', path: storagePath }})
       await brain3.init()
       expect((await brain3.find({ type: 'concept' })).length).toBe(0)
     } finally {
@@ -177,7 +177,7 @@ describe('Clear Persistence Bug Fix (v5.10.4)', () => {
   })
 
   it('should clear both entities and relations', async () => {
-    const brain1 = new Brainy({ storage: { type: 'filesystem', path: testStoragePath }})
+    const brain1 = new Brainy({ requireSubtype: false, storage: { type: 'filesystem', path: testStoragePath }})
     await brain1.init()
 
     // Add graph data
@@ -194,7 +194,7 @@ describe('Clear Persistence Bug Fix (v5.10.4)', () => {
     await brain1.clear()
 
     // Create new instance
-    const brain2 = new Brainy({ storage: { type: 'filesystem', path: testStoragePath }})
+    const brain2 = new Brainy({ requireSubtype: false, storage: { type: 'filesystem', path: testStoragePath }})
     await brain2.init()
 
     // Verify everything is cleared
@@ -204,7 +204,7 @@ describe('Clear Persistence Bug Fix (v5.10.4)', () => {
   })
 
   it('should handle clear() on empty storage', async () => {
-    const brain = new Brainy({ storage: { type: 'filesystem', path: testStoragePath }})
+    const brain = new Brainy({ requireSubtype: false, storage: { type: 'filesystem', path: testStoragePath }})
     await brain.init()
 
     // Clear without adding any data
@@ -219,7 +219,7 @@ describe('Clear Persistence Bug Fix (v5.10.4)', () => {
 
 describe('Clear() works for MemoryStorage', () => {
   it('should clear memory storage completely', async () => {
-    const brain1 = new Brainy({ storage: { type: 'memory' }})
+    const brain1 = new Brainy({ requireSubtype: false, storage: { type: 'memory' }})
     await brain1.init()
 
     await brain1.add({ data:'Test', type: 'concept' })