feat(ui): add relationship management features in schema editor

- Implement functionality to create, update, delete, and view relationships between tables.
- Introduce new UI screens for managing relationships, including forms for adding and editing relationships.
- Enhance table editor with navigation to relationship management.
- Ensure relationships are displayed in a structured table format for better usability.

pkg/inspector/doc.go

@@ -0,0 +1,40 @@
+// Package inspector provides database introspection capabilities for live databases.
+//
+// # Overview
+//
+// The inspector package contains utilities for connecting to live databases and
+// extracting their schema information through system catalog queries and metadata
+// inspection.
+//
+// # Features
+//
+//   - Database connection management
+//   - Schema metadata extraction
+//   - Table structure analysis
+//   - Constraint and index discovery
+//   - Foreign key relationship mapping
+//
+// # Supported Databases
+//
+//   - PostgreSQL (via pgx driver)
+//   - SQLite (via modernc.org/sqlite driver)
+//
+// # Usage
+//
+// This package is used internally by database readers (pgsql, sqlite) to perform
+// live schema introspection:
+//
+//	inspector := inspector.NewPostgreSQLInspector(connString)
+//	schemas, err := inspector.GetSchemas()
+//	tables, err := inspector.GetTables(schemaName)
+//
+// # Architecture
+//
+// Each database type has its own inspector implementation that understands the
+// specific system catalogs and metadata structures of that database system.
+//
+// # Security
+//
+// Inspectors use read-only operations and never modify database structure.
+// Connection credentials should be handled securely.
+package inspector