add new feature: show long-term memory records under the specified path

[Char1iee]

This PR adds support for viewing long-term memory records for a selected memory store and actor.
Changes include:

• Displays long-term memory records below the sessions/events view
• Resolves memory namespaces from memory strategy configuration
• Adds optional LONG_TERM_MEMORY_NAMESPACE_PATH env configuration
• Adds a direct Actor ID search so users can open an actor without relying on the first 100 listed actors
• Normalizes datetime sorting to avoid comparing timezone-aware and timezone-naive values