Cleanup: remove deprecated BlackListManager, unify HttpClient via IHttpClientFactory, deduplicate IPC encryption

[JusterZhu]

Summary

Three cleanup and hardening changes that reduce code debt and improve resource management:

1. Remove deprecated BlackListManager (#412)

• Deleted the obsolete \BlackListManager\ singleton class
• Extracted \IBlackListMatcher\ interface into its own file
• Removed fallback ?? BlackListManager.Instance\ references in \StorageManager.ReadFileNode()\
• Updated \BlackListDefaults\ comment

2. Unify HttpClient via IHttpClientFactory

• Added \Microsoft.Extensions.Http\ package (all 3 TFMs)
• Created \HttpClientFactoryProvider\ — lazy singleton wrapping \ServiceCollection\ → \IHttpClientFactory\
• Replaced all
  ew HttpClient()\ calls in \ClientUpdateStrategy, \SilentPollOrchestrator, \OSSUpdateStrategy\ with factory-created clients
• Removed manual \HttpClient.Dispose()\ calls (factory manages lifecycle)
• Converted \HttpClient.Timeout\ to \CancellationTokenSource\ for timeout control

3. Deduplicate IPC encryption

• Created \IpcEncryption\ — shared AES encryption utility class
• Refactored \Environments\ and \EncryptedFileProcessInfoProvider\ to delegate to \IpcEncryption\
• Fixed file name typo: \Muti\ → \Multi\ (4 event args files)
• Deleted stale
  et9.0\ bin/obj directories
• Deleted \ConfiginfoBuilder-Example.cs\ (example code in src)

Files changed

• 14 files modified | +3 new files | -3 deleted files | net -306 lines