fix: auto-convert ObjectId strings in find tool filters (#6)

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Fixes #6

Problem

When querying MongoDB through the find tool, string values in ID fields aren't being converted to ObjectId instances, causing queries to fail silently.

Solution

Added automatic detection and conversion of string values to ObjectId instances for ID fields (those ending with "Id" or "_id") when they match the ObjectId format. The conversion handles nested objects and includes error handling.

Testing

Manually verified with various ID fields and query combinations, confirming that:

• String-to-ObjectId conversion works correctly
• Mixed condition queries work
• Nested objects are processed
• Invalid strings are handled gracefully