fix: use shared fsnotify watcher to avoid 'too many open files' error

[johnlanni]

Problem

The API server crashes with panic: too many open files when creating REST storage for resources.

Root cause: Each resource type (ConfigMap, Secret, Ingress, etc.) creates its own fsnotify.Watcher instance in NewFileREST(), which consumes file descriptors. When the number of resource types exceeds the system limit, the application crashes.

Solution

Use a shared fsnotify.Watcher across all fileREST instances:

1. Create one global watcher in completedConfig.New() for File storage mode
2. Pass the shared watcher to all NewFileREST() calls
3. Update Destroy() to not close the watcher (managed by server lifecycle)

Changes

• src/apiserver/pkg/apiserver/apiserver.go: Create and pass shared watcher
• src/apiserver/pkg/registry/file_rest.go: Accept shared watcher parameter, remove per-instance watcher creation

Testing

Before: Application crashes with "too many open files" when registering multiple resources
After: All resources share one watcher, file descriptor usage reduced significantly

Fixes the panic reported in production environments.

[lingma-agents]

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🔄 分支流向: fix/shared-watcher ➜ main

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📒 文件清单 （2 个文件）

📝 变更: 2 个文件

📝 变更文件:

• src/apiserver/pkg/apiserver/apiserver.go
• src/apiserver/pkg/registry/file_rest.go

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