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/index.ts

@@ -138,9 +138,6 @@ import {
   embeddingFunctions
 } from './utils/embedding.js'
 
-// Export worker utilities
-import { executeInThread, cleanupWorkerPools } from './utils/workerUtils.js'
-
 // Export logging utilities
 import { 
   logger, 
@@ -153,11 +150,6 @@ import {
 
 
 // Export performance and optimization utilities
-import {
-  getGlobalSocketManager,
-  AdaptiveSocketManager
-} from './utils/adaptiveSocketManager.js'
-
 import {
   getGlobalBackpressure,
   AdaptiveBackpressure
@@ -169,16 +161,7 @@ import {
 } from './utils/performanceMonitor.js'
 
 // Export environment utilities
-import {
-  isBrowser,
-  isNode,
-  isWebWorker,
-  areWebWorkersAvailable,
-  areWorkerThreadsAvailable,
-  areWorkerThreadsAvailableSync,
-  isThreadingAvailable,
-  isThreadingAvailableAsync
-} from './utils/environment.js'
+import { isNode } from './utils/environment.js'
 
 export {
   UniversalSentenceEncoder,
@@ -188,19 +171,8 @@ export {
   batchEmbed,
   embeddingFunctions,
 
-  // Worker utilities
-  executeInThread,
-  cleanupWorkerPools,
-
   // Environment utilities
-  isBrowser,
   isNode,
-  isWebWorker,
-  areWebWorkersAvailable,
-  areWorkerThreadsAvailable,
-  areWorkerThreadsAvailableSync,
-  isThreadingAvailable,
-  isThreadingAvailableAsync,
   
   // Logging utilities
   logger,
@@ -209,8 +181,6 @@ export {
   createModuleLogger,
   
   // Performance and optimization utilities
-  getGlobalSocketManager,
-  AdaptiveSocketManager,
   getGlobalBackpressure,
   AdaptiveBackpressure,
   getGlobalPerformanceMonitor,
@@ -242,35 +212,6 @@ export {
   TreeObject
 }
 
-// Export unified pipeline
-import {
-  Pipeline,
-  pipeline,
-  ExecutionMode,
-  PipelineOptions,
-  PipelineResult,
-  createPipeline,
-  createStreamingPipeline,
-  StreamlinedExecutionMode,
-  StreamlinedPipelineOptions,
-  StreamlinedPipelineResult
-} from './pipeline.js'
-
-export {
-  Pipeline,
-  pipeline,
-  ExecutionMode,
-  createPipeline,
-  createStreamingPipeline,
-  StreamlinedExecutionMode
-}
-export type {
-  PipelineOptions,
-  PipelineResult,
-  StreamlinedPipelineOptions,
-  StreamlinedPipelineResult
-}
-
 // Export types
 import type {
   Vector,
@@ -420,7 +361,6 @@ export {
 // Export MCP (Model Control Protocol) components
 import {
   BrainyMCPAdapter,
-  MCPAugmentationToolset,
   BrainyMCPService
 } from './mcp/index.js' // Import from mcp/index.js
 import {
@@ -439,7 +379,6 @@ import {
 export {
   // MCP classes
   BrainyMCPAdapter,
-  MCPAugmentationToolset,
   BrainyMCPService,
 
   // MCP types