Enhancement: Consider Result<T, Error> type for consistent error handling

[mapitman]

Evaluate adopting Result<T, Error> type pattern for more consistent error handling across services.

Currently:

• Some methods return nullable types: Task<T?>
• Some return empty collections on failure
• Some throw exceptions
• Error logging via IProgressNotifier

Benefits of Result<T, Error>:

• Explicit error representation
• Type-safe error handling
• Better composability
• Clearer failure modes

Priority: Medium - Should address if error handling complexity increases