feat(8.0)!: delete fork/branch/commit/history/versions — superseded by the Db API

The COW version-control surface (fork, branches, checkout, commit,
getHistory/streamHistory, asOfCommit, brain.versions) is gone, along with
its subsystems: src/versioning/, the COW object store (CommitLog,
CommitObject, RefManager, TreeObject), HistoricalStorageAdapter, and the
TypeAwareHNSWIndex path it kept alive. The Db API (now/transact/asOf/
with/persist/restore) is the one versioning model in 8.0.

Survivors and replacements:
- BlobStorage survives (the VFS stores file content through it), relocated
  to src/storage/blobStorage.ts with binaryDataCodec.ts; its adapter
  interface is now BlobStoreAdapter, slimmed to the consumed surface
  (write/read/has/delete/getMetadata + MIME-aware compression policy).
- brain.migrate() backup branches are replaced by persist-before-migrate:
  MigrateOptions.backupTo persists a hard-link snapshot of the current
  generation before any transform runs; MigrationResult.backupPath reports
  it, and brain.restore(path) brings it back wholesale.
- CLI: cow.ts (fork/branch/checkout/history/migrate) is replaced by
  snapshot.ts — snapshot <path>, restore <path>, history (tx-log),
  generation.
- New public read API: brain.transactionLog({limit}) exposes the reified
  tx-log (generation/timestamp/meta, newest first) that backs the CLI
  history command; TxLogEntry is exported.

Tests: superseded suites deleted; fork/commit blocks excised from shared
suites; BlobStorage tests relocated + reworked against the slimmed store;
migration tests now prove the backupTo snapshot/restore round trip; new
transactionLog coverage in db-mvcc.

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

@@ -2,7 +2,6 @@
  * Integration tests for Memory Enhancements (v5.11.0)
  *
  * End-to-end tests verifying:
- * - streamHistory() works in production scenarios
  * - Container detection works correctly
  * - Memory limits are applied correctly
  * - getMemoryStats() provides accurate information
@@ -40,86 +39,6 @@ describe('Memory Enhancements Integration (v5.11.0)', () => {
     })
   })
 
-  describe('Production Workflow: Consumer Snapshot Timeline', () => {
-    it('should stream 1000 snapshots efficiently', async () => {
-      const brain = new Brainy({ requireSubtype: false,
-        storage: {
-          type: 'filesystem',
-          options: { path: testDir }
-        },
-        silent: true
-      })
-
-      await brain.init()
-
-      // Create a realistic workflow: user creates entities and saves snapshots
-      for (let i = 0; i < 100; i++) {
-        // Add 10 entities
-        for (let j = 0; j < 10; j++) {
-          await brain.add({
-            type: 'document',
-            data: `Chapter ${i}, Section ${j}`
-          })
-        }
-
-        // Save snapshot
-        await brain.commit({ message: `Version ${i}`, captureState: true })
-      }
-
-      // Stream history efficiently
-      const snapshots: string[] = []
-      const startTime = Date.now()
-
-      for await (const commit of brain.streamHistory({ limit: 100 })) {
-        snapshots.push(commit.message)
-      }
-
-      const duration = Date.now() - startTime
-
-      expect(snapshots.length).toBe(100)
-      expect(duration).toBeLessThan(5000) // Should complete in < 5s
-
-      await brain.close()
-    })
-
-    it('should handle large snapshot with filtering', async () => {
-      const brain = new Brainy({ requireSubtype: false,
-        storage: {
-          type: 'filesystem',
-          options: { path: testDir }
-        },
-        silent: true
-      })
-
-      await brain.init()
-
-      // Create snapshots by different authors
-      for (let i = 0; i < 50; i++) {
-        await brain.add({ type: 'document', data: `Content ${i}` })
-
-        await brain.commit({
-          message: `Snapshot ${i}`,
-          author: i % 3 === 0 ? 'alice' : i % 3 === 1 ? 'bob' : 'charlie',
-          captureState: true
-        })
-      }
-
-      // Stream only alice's snapshots
-      const aliceSnapshots: any[] = []
-
-      for await (const commit of brain.streamHistory({ author: 'alice', limit: 100 })) {
-        aliceSnapshots.push(commit)
-      }
-
-      expect(aliceSnapshots.length).toBeGreaterThan(0)
-      aliceSnapshots.forEach(commit => {
-        expect(commit.author).toBe('alice')
-      })
-
-      await brain.close()
-    })
-  })
-
   describe('Production Workflow: Cloud Run Deployment', () => {
     it('should detect 4GB Cloud Run container and set optimal limits', async () => {
       process.env.CLOUD_RUN_MEMORY = '4Gi'
@@ -190,51 +109,6 @@ describe('Memory Enhancements Integration (v5.11.0)', () => {
     })
   })
 
-  describe('Combined Features: Stream + Memory Management', () => {
-    it('should stream large histories within memory limits', async () => {
-      process.env.CLOUD_RUN_MEMORY = '2Gi'
-
-      const brain = new Brainy({ requireSubtype: false,
-        storage: {
-          type: 'filesystem',
-          options: { path: testDir }
-        },
-        silent: true
-      })
-
-      await brain.init()
-
-      // Create many snapshots
-      for (let i = 0; i < 200; i++) {
-        await brain.add({ type: 'document', data: `Data ${i}` })
-
-        if (i % 5 === 0) {
-          await brain.commit({ message: `Checkpoint ${i / 5}`, captureState: true })
-        }
-      }
-
-      // Verify memory limits
-      const stats = brain.getMemoryStats()
-      expect(stats.limits.maxQueryLimit).toBe(5000) // 2GB * 0.25
-
-      // Stream all snapshots (should be ~40)
-      const heapBefore = process.memoryUsage().heapUsed
-
-      let count = 0
-      for await (const commit of brain.streamHistory({ limit: 100 })) {
-        count++
-      }
-
-      const heapAfter = process.memoryUsage().heapUsed
-      const heapGrowth = heapAfter - heapBefore
-
-      expect(count).toBeGreaterThan(0)
-      expect(heapGrowth).toBeLessThan(20 * 1024 * 1024) // < 20MB growth
-
-      await brain.close()
-    })
-  })
-
   describe('Memory Stats API', () => {
     it('should provide actionable recommendations', async () => {
       process.env.CLOUD_RUN_MEMORY = '4Gi'
@@ -352,32 +226,5 @@ describe('Memory Enhancements Integration (v5.11.0)', () => {
 
       await brain.close()
     })
-
-    it('should keep getHistory() working as before', async () => {
-      const brain = new Brainy({ requireSubtype: false,
-        storage: {
-          type: 'filesystem',
-          options: { path: testDir }
-        },
-        silent: true
-      })
-
-      await brain.init()
-
-      // Create some snapshots
-      for (let i = 0; i < 10; i++) {
-        await brain.add({ type: 'note', data: `Test ${i}` })
-        await brain.commit({ message: `Snapshot ${i}`, captureState: true })
-      }
-
-      // Old API still works
-      const history = await brain.getHistory({ limit: 10 })
-
-      expect(history.length).toBe(10)
-      expect(history[0]).toHaveProperty('hash')
-      expect(history[0]).toHaveProperty('message')
-
-      await brain.close()
-    })
   })
 })