Remove test migration file and update docs

- Remove placeholder dm1.py migration file that shouldn't be committed
- Update migrations.md to clarify migrate vs om migrate differences
- Document deprecation of standalone migrate command

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: abrookins

docs/migrations.md

@@ -11,15 +11,17 @@ Redis OM provides two CLI interfaces:
 
 ### Unified CLI (Recommended)
 ```bash
-om migrate          # Schema migrations  
+om migrate          # File-based schema migrations with rollback support
 om migrate-data     # Data migrations
 ```
 
-### Individual Commands (Backward Compatible)
+### Legacy Command (Deprecated)
 ```bash
-migrate             # Schema migrations (original command still works)
+migrate             # Automatic schema migrations (deprecated - use om migrate)
 ```
 
+⚠️ **Important**: The standalone `migrate` command uses automatic migrations (immediate DROP+CREATE) and is deprecated. Use `om migrate` for the new file-based migration system with rollback support.
+
 ## Schema Migrations
 
 Schema migrations manage RediSearch index definitions. When you change field types, indexing options, or other schema properties, Redis OM automatically detects these changes and can update your indices accordingly.
@@ -51,9 +53,25 @@ om migrate run
 om migrate run --migrations-dir myapp/schema-migrations
 ```
 
-> **Note**: The original `migrate` command is still available for backward compatibility.
+> **Note**: The legacy `migrate` command performs automatic migrations without file tracking and is deprecated. Use `om migrate` for production deployments.
+
+### Migration Approaches
+
+Redis OM provides two approaches to schema migrations:
+
+#### File-based Migrations (`om migrate`) - Recommended
+- **Controlled**: Migrations are saved as versioned files
+- **Rollback**: Previous schemas can be restored
+- **Team-friendly**: Migration files can be committed to git
+- **Production-safe**: Explicit migration approval workflow
+
+#### Automatic Migrations (`migrate`) - Deprecated  
+- **Immediate**: Detects and applies changes instantly
+- **No rollback**: Cannot undo schema changes
+- **Development-only**: Suitable for rapid prototyping
+- **⚠️ Deprecated**: Use `om migrate` for production
 
-### How Schema Migration Works
+### How File-based Migration Works
 
 1. **Detection**: Auto-migrator detects index changes from your models
 2. **Snapshot**: `om migrate create` writes a migration file capturing old/new index schemas