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/memory-enhancements-v5.11.0.test.ts

@@ -42,7 +42,7 @@ describe('Memory Enhancements Integration (v5.11.0)', () => {
 
   describe('Production Workflow: Consumer Snapshot Timeline', () => {
     it('should stream 1000 snapshots efficiently', async () => {
-      const brain = new Brainy({
+      const brain = new Brainy({ requireSubtype: false,
         storage: {
           type: 'filesystem',
           options: { path: testDir }
@@ -83,7 +83,7 @@ describe('Memory Enhancements Integration (v5.11.0)', () => {
     })
 
     it('should handle large snapshot with filtering', async () => {
-      const brain = new Brainy({
+      const brain = new Brainy({ requireSubtype: false,
         storage: {
           type: 'filesystem',
           options: { path: testDir }
@@ -124,7 +124,7 @@ describe('Memory Enhancements Integration (v5.11.0)', () => {
     it('should detect 4GB Cloud Run container and set optimal limits', async () => {
       process.env.CLOUD_RUN_MEMORY = '4Gi'
 
-      const brain = new Brainy({
+      const brain = new Brainy({ requireSubtype: false,
         storage: { type: 'memory' },
         silent: true
       })
@@ -154,7 +154,7 @@ describe('Memory Enhancements Integration (v5.11.0)', () => {
     it('should allow manual override for power users in containers', async () => {
       process.env.CLOUD_RUN_MEMORY = '4Gi'
 
-      const brain = new Brainy({
+      const brain = new Brainy({ requireSubtype: false,
         storage: { type: 'memory' },
         maxQueryLimit: 50000, // Override auto-detection
         silent: true
@@ -173,7 +173,7 @@ describe('Memory Enhancements Integration (v5.11.0)', () => {
     })
 
     it('should use reservedQueryMemory for fine-grained control', async () => {
-      const brain = new Brainy({
+      const brain = new Brainy({ requireSubtype: false,
         storage: { type: 'memory' },
         reservedQueryMemory: 2 * 1024 * 1024 * 1024, // Reserve 2GB
         silent: true
@@ -194,7 +194,7 @@ describe('Memory Enhancements Integration (v5.11.0)', () => {
     it('should stream large histories within memory limits', async () => {
       process.env.CLOUD_RUN_MEMORY = '2Gi'
 
-      const brain = new Brainy({
+      const brain = new Brainy({ requireSubtype: false,
         storage: {
           type: 'filesystem',
           options: { path: testDir }
@@ -239,7 +239,7 @@ describe('Memory Enhancements Integration (v5.11.0)', () => {
     it('should provide actionable recommendations', async () => {
       process.env.CLOUD_RUN_MEMORY = '4Gi'
 
-      const brain = new Brainy({
+      const brain = new Brainy({ requireSubtype: false,
         storage: { type: 'memory' },
         silent: true
       })
@@ -266,7 +266,7 @@ describe('Memory Enhancements Integration (v5.11.0)', () => {
       // Simulate production issue: container detected but low free memory
       process.env.CLOUD_RUN_MEMORY = '4Gi'
 
-      const brain = new Brainy({
+      const brain = new Brainy({ requireSubtype: false,
         storage: { type: 'memory' },
         silent: true
       })
@@ -291,7 +291,7 @@ describe('Memory Enhancements Integration (v5.11.0)', () => {
     it('should work optimally with no configuration', async () => {
       process.env.CLOUD_RUN_MEMORY = '4Gi'
 
-      const brain = new Brainy({
+      const brain = new Brainy({ requireSubtype: false,
         storage: { type: 'memory' },
         silent: true
       })
@@ -318,7 +318,7 @@ describe('Memory Enhancements Integration (v5.11.0)', () => {
     it('should work on bare metal without containers', async () => {
       // No container env vars
 
-      const brain = new Brainy({
+      const brain = new Brainy({ requireSubtype: false,
         storage: { type: 'memory' },
         silent: true
       })
@@ -337,7 +337,7 @@ describe('Memory Enhancements Integration (v5.11.0)', () => {
 
   describe('Backward Compatibility', () => {
     it('should not break existing code', async () => {
-      const brain = new Brainy({
+      const brain = new Brainy({ requireSubtype: false,
         storage: { type: 'memory' },
         silent: true
       })
@@ -354,7 +354,7 @@ describe('Memory Enhancements Integration (v5.11.0)', () => {
     })
 
     it('should keep getHistory() working as before', async () => {
-      const brain = new Brainy({
+      const brain = new Brainy({ requireSubtype: false,
         storage: {
           type: 'filesystem',
           options: { path: testDir }