This PR adds a new piece for Klaviyo, a marketing automation platform.

Features Included:

• Authentication: Private API Key (SecretText).
• Actions:
  • Create/Update Profile
  • Add/Remove Profile from List
  • Create List
  • Find Profile by Email
• Triggers:
  • New Profile (Polling)
  • Profile Added to List (Polling)

Technical Notes:

• Strictly typed using @activepieces/pieces-framework.
• Implements stateful polling for triggers using context.store.
• Verified against Klaviyo API v2024-10-15.

/claim #8284