chore: address review comments

[tianzhou]

follow up: #156

[Copilot]

Pull Request Overview

This PR addresses review comments from a previous pull request by improving code documentation and fixing a bug in constraint handling. The changes focus on clarifying the topological sorting algorithm's cycle-breaking strategy and correcting schema resolution for foreign key constraints.

Key changes:

• Added comprehensive inline documentation explaining the cycle-breaking strategy in topological sorting for both tables and views
• Fixed a bug where shouldDeferConstraint was incorrectly using constraint.Schema instead of table.Schema when the referenced schema was empty
• Enhanced the function call regex pattern to properly match schema-qualified function names with multiple dot separators

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
internal/diff/topological.go	Added detailed comments explaining the cycle-breaking strategy in Kahn's algorithm for both table and view sorting
internal/diff/table.go	Fixed schema resolution bug by passing the table parameter and using table.Schema instead of constraint.Schema
internal/diff/diff.go	Updated regex pattern to correctly capture schema-qualified function names with multiple segments

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.