fix: Update SDK version handling in API and documentation to treat null SDK values as SDK6 (legacy scenes)

bin/README.md

@@ -26,3 +26,59 @@ npm run serve              # Process messages
 ```
 
 **See:** [SQS Setup Guide](../docs/sqs-setup.md) for detailed SQS configuration.
+
+---
+
+## `populateSdk.ts`
+
+One-time script to backfill the `sdk` column in the database by fetching `runtimeVersion` from scene.json files via Catalyst (for Genesis City places) and Worlds Content Server (for worlds).
+
+### Usage
+
+```bash
+# Development environment
+npm run populate:sdk:dev
+
+# Staging environment
+npm run populate:sdk:stg
+
+# Production environment
+npm run populate:sdk:prd
+```
+
+### Options
+
+| Option      | Description                                        |
+| ----------- | -------------------------------------------------- |
+| `--dry-run` | Preview changes without modifying the database     |
+| `--limit N` | Process only N records                             |
+| `--places`  | Process only Genesis City places (excludes worlds) |
+| `--worlds`  | Process only worlds (excludes places)              |
+
+### Examples
+
+```bash
+# Dry run with limit of 10 records in development
+npm run populate:sdk:dev -- --dry-run --limit 10
+
+# Process only worlds in staging
+npm run populate:sdk:stg -- --worlds
+
+# Full production run (use with caution)
+npm run populate:sdk:prd
+```
+
+### Environment Variables
+
+| Variable                    | Description                  | Default                                          |
+| --------------------------- | ---------------------------- | ------------------------------------------------ |
+| `CONNECTION_STRING`         | PostgreSQL connection string | (required)                                       |
+| `CATALYST_URL`              | Catalyst server URL          | `https://peer.decentraland.org`                  |
+| `WORLDS_CONTENT_SERVER_URL` | Worlds Content Server URL    | `https://worlds-content-server.decentraland.org` |
+
+### How It Works
+
+1. Queries database for records with `sdk IS NULL`
+2. For Genesis City places: Fetches scene entities from Catalyst API and extracts `runtimeVersion` from scene.json
+3. For Worlds: Fetches world metadata from Worlds Content Server using world name/URN
+4. Updates database records with the extracted SDK version