Module merge 

Deep-merge of serde_json::Value for matrix-row overrides.

Rules:

• Two objects merge recursively, keys from overlay win on collision.
• Anything else (scalar, array, null) — overlay replaces base wholesale.
• Arrays do not element-merge or concatenate. This is deliberate: matrix rows that need to add to an inherited array should redeclare it in full.

Functions

merge_value

In-place deep-merge overlay into base. See module docs for rules.