Develop Tree Diffing Algorithm

[stifskere]

Sub-issue of #3

Objective

Implement AST diffing to identify schema changes.

Tasks

Stage 1: PostgreSQL CREATE TABLE (priority)

• Define comparison logic for tables, columns, and constraints.
• Detect add, remove, and modify changes.
• Output diff forest representing these changes.

Stage 2: Full MVP / Other Dialects

• Extend diff to support additional node types (indexes, triggers).
• Handle rename detection and advanced changes.

Note: Stage 2 is low priority; focus on Stage 1 to enable usage within Flaky.