chore(8.0): Phase C + D + E — config simplification, TODO sweep, test race fix

Phase C: storageAutoConfig.ts rewrite (376 LOC → ~110 LOC). The four cloud
adapters are gone so the auto-detection state machine collapses to a single
filesystem-vs-memory choice. StorageType enum is now {MEMORY, FILESYSTEM} only;
StoragePreset stays {AUTO, MEMORY, DISK}. zeroConfig.ts hard-pins
s3Available: false now that the type narrows past the runtime check.

Phase D: TODO/FIXME sweep in src/. Removed seven stale markers. The CLI cow
migrate command's backup path now uses fs.cp with recursive + force:false
instead of a TODO placeholder.

Phase E: skipped-test deletion + parallel-test race fix.
  - storage-batch-operations.test.ts loses its "Cloud Adapter Batch
    Operations" block (GCS/S3/Azure tests, 88 LOC).
  - cow-full-integration.test.ts loses its skipped "S3 adapter" test.
  - create-entities-default.test.ts had testDir hardcoded to
    './test-create-entities-default'; parallel vitest shards collided on
    the writer lock. testDir is now os.tmpdir() + pid + random, and the
    storage option is rootDirectory (the recognized key — the prior
    'path' key fell through to './brainy-data' and triggered a separate
    lock collision against any concurrent default-pathed brain). Added
    afterEach brain.close() so the lock releases before rmSync.

src/cli/interactive.ts

@@ -7,7 +7,6 @@
 
 import chalk from 'chalk'
 import inquirer from 'inquirer'
-// import fuzzy from 'fuzzy'  // TODO: Install fuzzy package or remove dependency
 import ora from 'ora'
 import { Brainy } from '../brainy.js'
 import { getBrainyVersion } from '../utils/version.js'