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.

doc.go

@@ -0,0 +1,108 @@
+// Package relspecgo provides bidirectional conversion between database schema formats.
+//
+// RelSpec is a comprehensive database schema tool that reads, writes, and transforms
+// database schemas across multiple formats including live databases, ORM models,
+// schema definition languages, and data interchange formats.
+//
+// # Features
+//
+//   - Read from 15+ formats: PostgreSQL, SQLite, DBML, GORM, Prisma, Drizzle, and more
+//   - Write to 15+ formats: SQL, ORM models, schema definitions, JSON/YAML
+//   - Interactive TUI editor for visual schema management
+//   - Schema diff and merge capabilities
+//   - Format-agnostic intermediate representation
+//
+// # Architecture
+//
+// RelSpec uses a hub-and-spoke architecture with models.Database as the central type:
+//
+//	Input Format → Reader → models.Database → Writer → Output Format
+//
+// This allows any supported input format to be converted to any supported output format
+// without requiring N² conversion implementations.
+//
+// # Key Packages
+//
+//   - pkg/models: Core data structures (Database, Schema, Table, Column, etc.)
+//   - pkg/readers: Input format readers (dbml, pgsql, gorm, etc.)
+//   - pkg/writers: Output format writers (dbml, pgsql, gorm, etc.)
+//   - pkg/ui: Interactive terminal UI for schema editing
+//   - pkg/diff: Schema comparison and difference detection
+//   - pkg/merge: Schema merging utilities
+//   - pkg/transform: Validation and normalization
+//
+// # Installation
+//
+//	go install git.warky.dev/wdevs/relspecgo/cmd/relspec@latest
+//
+// # Usage
+//
+// Command-line conversion:
+//
+//	relspec convert --from dbml --from-path schema.dbml \
+//	                --to gorm --to-path ./models
+//
+// Interactive editor:
+//
+//	relspec edit --from pgsql --from-conn "postgres://..." \
+//	             --to dbml --to-path schema.dbml
+//
+// Schema comparison:
+//
+//	relspec diff --source-type pgsql --source-conn "postgres://..." \
+//	             --target-type dbml --target-path schema.dbml
+//
+// Merge schemas:
+//
+//	relspec merge --target schema1.dbml --sources schema2.dbml,schema3.dbml
+//
+// # Supported Formats
+//
+// Input/Output Formats:
+//   - dbml: Database Markup Language
+//   - dctx: DCTX schema files
+//   - drawdb: DrawDB JSON format
+//   - graphql: GraphQL schema definition
+//   - json: JSON schema representation
+//   - yaml: YAML schema representation
+//   - gorm: Go GORM models
+//   - bun: Go Bun models
+//   - drizzle: TypeScript Drizzle ORM
+//   - prisma: Prisma schema language
+//   - typeorm: TypeScript TypeORM entities
+//   - pgsql: PostgreSQL (live DB or SQL)
+//   - sqlite: SQLite (database file or SQL)
+//
+// # Library Usage
+//
+// RelSpec can be used as a Go library:
+//
+//	import (
+//	    "git.warky.dev/wdevs/relspecgo/pkg/models"
+//	    "git.warky.dev/wdevs/relspecgo/pkg/readers/dbml"
+//	    "git.warky.dev/wdevs/relspecgo/pkg/writers/gorm"
+//	)
+//
+//	// Read DBML
+//	reader := dbml.NewReader(&readers.ReaderOptions{
+//	    FilePath: "schema.dbml",
+//	})
+//	db, err := reader.ReadDatabase()
+//
+//	// Write GORM models
+//	writer := gorm.NewWriter(&writers.WriterOptions{
+//	    OutputPath:  "./models",
+//	    PackageName: "models",
+//	})
+//	err = writer.WriteDatabase(db)
+//
+// # Documentation
+//
+// Full documentation available at: https://git.warky.dev/wdevs/relspecgo
+//
+// API documentation: go doc git.warky.dev/wdevs/relspecgo/...
+//
+// # License
+//
+// See LICENSE file in the repository root.
+package relspecgo