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/vfs/tree-operations.test.ts

@@ -13,7 +13,7 @@ describe('VFS Tree Operations', () => {
   let vfs: VirtualFileSystem
 
   beforeEach(async () => {
-    brain = new Brainy()
+    brain = new Brainy({ requireSubtype: false })
     await brain.init({
       storage: {
         type: 'memory'  // Use in-memory storage for tests

tests/vfs/vfs-bug-fixes.unit.test.ts

@@ -16,7 +16,7 @@ describe('VFS Bug Fixes', () => {
 
   beforeEach(async () => {
     // Create fresh instance for each test
-    brain = new Brainy({
+    brain = new Brainy({ requireSubtype: false,
       storage: { type: 'memory' },
       embeddingModel: 'Q8'
     })

tests/vfs/vfs-bulkwrite-race.test.ts

@@ -21,7 +21,7 @@ describe('VFS bulkWrite Race Condition Fix', () => {
   let vfs: VirtualFileSystem
 
   beforeEach(async () => {
-    brain = new Brainy({
+    brain = new Brainy({ requireSubtype: false,
       storage: { type: 'memory' },
       embeddingModel: 'Q8'
     })

tests/vfs/vfs-initialization.unit.test.ts

@@ -12,7 +12,7 @@ describe('VFS Initialization', () => {
 
   describe('Auto-Initialization (v5.1.0+)', () => {
     it('should auto-initialize VFS during brain.init()', async () => {
-      const brain = new Brainy({
+      const brain = new Brainy({ requireSubtype: false,
         storage: { type: 'memory' },
         silent: true
       })
@@ -29,7 +29,7 @@ describe('VFS Initialization', () => {
     })
 
     it('should automatically create root directory on brain.init()', async () => {
-      const brain = new Brainy({
+      const brain = new Brainy({ requireSubtype: false,
         storage: { type: 'memory' },
         silent: true
       })
@@ -52,7 +52,7 @@ describe('VFS Initialization', () => {
     })
 
     it('should handle nested directories after brain.init()', async () => {
-      const brain = new Brainy({
+      const brain = new Brainy({ requireSubtype: false,
         storage: { type: 'memory' },
         silent: true
       })

tests/vfs/vfs-relationships.test.ts

@@ -15,7 +15,7 @@ describe('VFS Graph Relationships', () => {
   let brain: Brainy
 
   beforeEach(async () => {
-    brain = new Brainy()
+    brain = new Brainy({ requireSubtype: false })
     await brain.init()
     vfs = new VirtualFileSystem(brain)
     await vfs.init()

tests/vfs/vfs.unit.test.ts

@@ -16,7 +16,7 @@ describe('VirtualFileSystem - Production Tests', () => {
 
   beforeEach(async () => {
     // Create a fresh Brainy instance with in-memory storage for each test
-    brain = new Brainy({
+    brain = new Brainy({ requireSubtype: false,
       storage: { type: 'memory' },
       silent: true  // Reduce test output
     })
@@ -492,7 +492,7 @@ describe('VirtualFileSystem - Watch System', () => {
   let brain: Brainy
 
   beforeAll(async () => {
-    brain = new Brainy({ storage: { type: 'memory' }, silent: true })
+    brain = new Brainy({ requireSubtype: false, storage: { type: 'memory' }, silent: true })
     await brain.init()
     vfs = new VirtualFileSystem(brain)
     await vfs.init()