chore(8.0)!: drop browser support, cloud SDKs, legacy pipeline, dead threading

Brainy 8.0 is server-only. This commit takes the consequences seriously and
removes everything that was only there to keep browser/cloud/threading
surfaces alive.

Browser support drop (per the @deprecated notes in environment.ts):
  - isBrowser, isWebWorker, areWebWorkersAvailable, navigator.deviceMemory
    paths, window/document/self.onmessage code.
  - browser console.log in unified.ts, the 'browser' branch in
    autoConfiguration.ts (env enum + scaleUp cases), 'browser-cache' model
    path, MCP service environment value.
  - package.json browser field.
  - src/worker.ts (Web Worker entrypoint) deleted.

Cloud SDK removal (the four adapters were dropped in Phase 7; the SDKs
were the lingering tax):
  - @aws-sdk/client-s3, @azure/identity, @azure/storage-blob, and
    @google-cloud/storage removed from package.json. Lockfile drops the
    entire @aws/@azure/@google-cloud/@smithy transitive tree.
  - EnhancedS3Clear class deleted from enhancedClearOperations.ts (the
    only @aws-sdk/client-s3 consumer; the dynamic import sites went with
    it). EnhancedFileSystemClear stays.
  - src/utils/adaptiveSocketManager.ts deleted entirely (474 LOC of HTTPS
    socket-pool management for the dropped cloud HTTP handler).
    performanceMonitor.ts no longer reports a socketConfig; socket
    utilization is fixed at 0.

Dead threading subsystem:
  - executeInThread was imported by distance.ts and hnswIndex.ts but
    never called. It was scaffolding for a future "off-main-thread
    distance batch" optimization that never shipped.
  - src/utils/workerUtils.ts deleted (Web Worker code path + an
    unreachable Node Worker Threads code path).
  - environment.ts loses isThreadingAvailable, isThreadingAvailableAsync,
    areWorkerThreadsAvailable, areWorkerThreadsAvailableSync. All exports
    purged from index.ts and unified.ts.
  - autoConfiguration.ts drops AutoConfigResult.threadingAvailable.

Legacy plugin/augmentation pipeline:
  - src/pipeline.ts deleted. The whole file was a no-op stub for
    backwards compat — Pipeline class had no methods, no lifecycle hooks,
    no before/after callbacks. AugmentationPipeline, augmentationPipeline,
    createPipeline, createStreamingPipeline, StreamlinedPipelineOptions,
    StreamlinedPipelineResult, StreamlinedExecutionMode were all aliases
    for the same stub.
  - src/mcp/mcpAugmentationToolset.ts deleted. executePipeline always
    threw "deprecated", isValidAugmentationType always returned false,
    getAvailableTools always returned []. Dead surface.
  - BrainyMCPService no longer instantiates a toolset. TOOL_EXECUTION
    requests now return the standard UNSUPPORTED_REQUEST_TYPE error.
    'availableTools' system-info returns [] (was the same in practice).

Net: 22 files changed, ~6400 LOC deleted (including legacy code +
mechanical lockfile churn). Build clean, 1409/1409 tests pass.

src/unified.ts

@@ -1,74 +1,30 @@
 /**
- * Unified entry point for Brainy
- * This file exports everything from index.ts
- * Environment detection is handled here and made available to all components
+ * @module unified
+ * @description Unified entry point for Brainy. Re-exports the public surface
+ * from `index.js` and surfaces a tiny runtime-environment object the rest of
+ * the library can read.
+ *
+ * 8.0 supports Node-like runtimes only (Node.js, Bun, Deno); the browser
+ * detection helpers and Worker Thread plumbing are gone.
  */
 
-// CRITICAL: The TensorFlow.js environment patch is now centralized in setup.ts
-// We import setup.ts below which applies the necessary patches
-
-// CRITICAL: Import setup.js first to ensure TensorFlow.js environment patching
-// This MUST be the first import to prevent race conditions with TensorFlow.js initialization
-// Moving or removing this import will cause errors like "TextEncoder is not a constructor"
-// when the package is used in Node.js environments
-//
-// The setup.js file applies a patch that ensures TextEncoder/TextDecoder are properly
-// available to TensorFlow.js before it initializes its platform detection
 import './setup.js'
 
-// Import environment detection functions
-import { 
-  isBrowser, 
-  isNode, 
-  isWebWorker, 
-  isThreadingAvailable, 
-  isThreadingAvailableAsync, 
-  areWorkerThreadsAvailable 
-} from './utils/environment.js'
+import { isNode } from './utils/environment.js'
 
-// Export environment information with lazy evaluation
 export const environment = {
-  get isBrowser() {
-    return isBrowser()
-  },
   get isNode() {
     return isNode()
-  },
-  get isServerless() {
-    return !isBrowser() && !isNode()
-  },
-  isWebWorker: function() {
-    return isWebWorker()
-  },
-  get isThreadingAvailable() {
-    return isThreadingAvailable()
-  },
-  isThreadingAvailableAsync: function() {
-    return isThreadingAvailableAsync()
-  },
-  areWorkerThreadsAvailable: function() {
-    return areWorkerThreadsAvailable()
   }
 }
 
-// Make environment information available globally
 if (typeof globalThis !== 'undefined') {
-  (globalThis as any).__ENV__ = environment
+  ;(globalThis as any).__ENV__ = environment
 }
 
-// Log the detected environment
 console.log(
-  `Brainy running in ${
-    environment.isBrowser
-      ? 'browser'
-      : environment.isNode
-        ? 'Node.js'
-        : 'serverless/unknown'
-  } environment`
+  `Brainy running on ${environment.isNode ? 'Node-like runtime' : 'unknown runtime'}`
 )
 
-// Re-export everything from index.ts
 export * from './index.js'
-
-// Export the TensorFlow patch function for testing and manual use
 export { applyTensorFlowPatch } from './utils/textEncoding.js'