[Enhancement] Unified Plugin Management - Cluster Consistency and Monitoring (Part 2/3)

[WangzJi]

Is your feature request related to a problem? Please describe.
This is the second sub-issue of the Unified Plugin Management System #14049. It enables distributed state synchronization and cross-node availability checks.

Describe the solution you'd like

Goal

Enable distributed state synchronization and cross-node availability checks for plugin management.

Key Components

• Implement PluginStatePersistence supporting both local file storage and Raft propagation
• Develop Raft request models and the PluginStateProcessor
• Implement PluginAvailabilityMonitor and RPC handlers (PluginListRequest) to track cluster-wide status

Dependencies
Depends on Sub-issue #14077 (Core Framework and Plugin Integration) - requires the core SPI interfaces and UnifiedPluginManager to be implemented first.

Describe alternatives you've considered

• Using only local storage without Raft was considered but rejected to ensure cluster consistency
• Implementing availability monitoring as a separate sub-issue was considered but it's tightly coupled with state persistence

Additional context

• Related to Plugin Switch Management and Console Page #14049
• Depends on: Sub-issue [Enhancement] Unified Plugin Management - Core Framework and Plugin Integration (Part 1/3) #14077
• Blocks: Sub-issue # (Console UI needs cluster state data)
• This PR contains complex Raft logic and should be reviewed carefully for correctness

[github-actions]

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