test: add comprehensive unit tests for Sub Issue 13

Add comprehensive unit tests covering:
- Client/Upgrade mutual upgrade integration (ProcessInfo IPC, version chain, forcibly update)
- Differential upgrade full cycle (Clean/Dirty, binary files, nested directories, mixed operations)
- Event notification pipeline (all 7 event types, push upgrade simulation, multiple listeners)
- Parameter matrix combinations (UpdateOptions, Configinfo validation, auth schemes, blacklists)
- Real-world developer usage scenarios (minimal setup, full production chain, fluent API)
- StorageManager backup/restore tests
- PipelineContext and DiffPipeline tests

Results: CoreTest 111/112 pass, DifferentialTest 23/23 pass, ClientCoreTest 115/115 pass

Author: JusterZhu