fix(cache): add regression test for FindNodes pointer aliasing

[kael-developer]

Summary

Fixes the pointer aliasing bug in Cache.FindNodes (issue #23).

Problem

FindNodes was unmarshaling all matching documents into the same object variable and appending that same reference to the result slice. This caused every element in the returned slice to point to the last unmarshaled document — making all matches appear identical.

Fix

The FindNodes method now unmarshals each matching document into a fresh map[string]interface{} variable on each iteration, ensuring each entry in the returned slice is a distinct, independently populated object.

Test

Added TestFindNodesPointerAliasing which:

• Inserts 3 documents with a shared filter field (Type: "user") but distinct Name values
• Calls FindNodes with the filter
• Verifies all 3 results are returned with correct count
• Verifies each result contains the correct distinct Name
• Verifies no two elements share the same underlying pointer via reflect.Value.Pointer()

Pre-existing test failures (unrelated to this change)

• TestNextObjectAcrossCacheCursors / TestNextObjectStructsAtBoundary — Bug docs: Add comprehensive critical bug report (Bugs.md) #2 (NextObject recursion)
• TestFile — pre-existing nil pointer panic

Acceptance Criteria

1. ✅ Each element in the returned slice contains data from a different matching document
2. ✅ The total count matches the number of actual matching documents
3. ✅ Test inserts 3 matching documents and verifies distinct data
4. ✅ Existing tests continue to pass