Inconsistent naming of duplicated nodes

**Describe the bug (REQUIRED)**
The naming logic during duplication is inconsistent. Currently, duplicating node_1 results in node_ (stripping the number) instead of node_2. This breaks the numbering flow.

**Expected behavior (REQUIRED)**
Smart Increment: Implement logic to detect trailing numbers. When duplicating a node like node_1, the new node should be named node_2.

**Workaround (OPTIONAL):**
Manually renaming every duplicated node to maintain proper numbering.

From https://github.com/defold/defold/issues/11861

No file or test is named in the issue. Start by tracing the node-duplication naming logic in the Defold editor, using the linked issue 11861 for context. Done means duplicating node_1 produces node_2 and preserves the expected numbering flow.

Written by the indexing model from the issue text.