test(k8s): add conversation history tests

[rafeegnash]

Summary

• Add conversation_test.go with comprehensive test coverage for conversation history management
• Tests cover struct validation, persistence, utilities, and concurrent access

Test Coverage

• Struct Validation:

  • ConversationEntry fields
  • ClusterStatus fields and zero values

• Constants:

  • MaxHistoryEntries (20)
  • MaxAnswerLengthInContext (500)

• ConversationHistory Methods:

  • NewConversationHistory constructor
  • AddEntry with automatic trimming when exceeding max entries
  • GetRecentContext with limited entries
  • UpdateClusterStatus and GetClusterStatus
  • GetClusterStatusContext formatting
  • Clear method
  • Save and Load persistence to disk
  • JSON marshaling

• Utility Functions:

  • sanitizeFilename - handles special characters for safe file paths
  • truncateText - handles text truncation with ellipsis
  • extractServerVersion - parses kubectl version output

• Edge Cases:

  • Concurrent access safety (mutex verification)
  • Long answer truncation in context
  • Non-existent file loading
  • Empty and whitespace input handling

Test plan

• All tests pass locally
• Code formatted with go fmt
• Tests cover edge cases and concurrent access

Closes bgdnvk#68