fix: protect concurrent map access with mutexLock

[forrestIsRunning]

Description

This PR fixes concurrent map access issues in the promptRegistry. The race conditions occur in two main scenarios:

1. Background Polling vs Business Access

   • A background goroutine polls and updates the promptRegistry every 5 seconds (via pollPrompts)
   • Meanwhile, business logic reads the registry through GetOpenAIChatCompletionRequest
   • This creates a read/write race condition on the shared map

2. Multiple Client Requests

   • Multiple API requests can trigger GetOpenAIChatCompletionRequest simultaneously
   • Each request reads from the promptRegistry
   • While these reads occur, the background polling might update the map

Changes

• Added mutex lock protection in populatePromptRegistry() for map writes
• Ensured proper read lock usage in getPromptVersion()
• Protected all concurrent map access points with sync.RWMutex

[nirga]

Thanks!