Implement SQLite migration system

## Description
Add migration system for SQLite with SQLite-specific DDL limitations and workarounds.

## Requirements
- [ ] SQLite DDL operations (CREATE, DROP)
- [ ] ALTER TABLE limitations handling
- [ ] Table recreation for complex changes
- [ ] Index management
- [ ] Foreign key support
- [ ] Write comprehensive tests

## Acceptance Criteria
- SQLite migration support with limitations handled
- Table recreation for unsupported ALTER operations
- Proper foreign key handling
- Index management

## Files to create
- `beatrix_core/src/relational/migrations/sqlite.rs`

## Example Usage
```rust
Migration::new("add_user_column")
.alter_table("users", |table| {
table.add_column("phone", "TEXT");
})
.run(&db).await?; // Handles table recreation if needed
```