fix: preserve gameplay data and correct duel evaluation

- Preserve snake customizations across database migrations and merges.
- Lazily load optional storage backends for SQLite maintenance scripts.
- Match Apex territory and nearest-food tie-breaking semantics.
- Resolve duel occupancy after simultaneous movement and food growth.
- Recompute simulated head-to-head danger after body growth.
- Add regression coverage and declare the aiofiles dependency.

README.md

@@ -1,17 +1,14 @@
 # Battlesnake Python Starter Project
-
 An official Battlesnake template written in Python. Get started at [play.battlesnake.com](https://play.battlesnake.com).
 
 ![Battlesnake Logo](https://media.battlesnake.com/social/StarterSnakeGitHubRepos_Python.png)
 
-This project is a great starting point for anyone wanting to program their first Battlesnake in Python. It can be run locally or easily deployed to a cloud provider of your choosing. See the [Battlesnake API Docs](https://docs.battlesnake.com/api) for more detail. 
+This project is a great starting point for anyone wanting to program their first Battlesnake in Python. It can be run locally or easily deployed to a cloud provider of your choosing. See the [Battlesnake API Docs](https://docs.battlesnake.com/api) for more detail.
 
 ## Technologies Used
-
 This project uses [Python 3](https://www.python.org/) and [Flask](https://flask.palletsprojects.com/). It also comes with an optional [Dockerfile](https://docs.docker.com/engine/reference/builder/) to help with deployment.
 
 ## Run Your Battlesnake
-
 Install dependencies using pip
 
 ```sh
@@ -19,7 +16,6 @@ pip install -r requirements.txt
 ```
 
 Start your Battlesnake
-
 ```sh
 python main.py
 ```
@@ -39,19 +35,16 @@ Open [localhost:8000](http://localhost:8000) in your browser and you should see
 ```
 
 ## Play a Game Locally
-
 Install the [Battlesnake CLI](https://github.com/BattlesnakeOfficial/rules/tree/main/cli)
 * You can [download compiled binaries here](https://github.com/BattlesnakeOfficial/rules/releases)
 * or [install as a go package](https://github.com/BattlesnakeOfficial/rules/tree/main/cli#installation) (requires Go 1.18 or higher)
 
 Command to run a local game
-
 ```sh
 battlesnake play -W 11 -H 11 --name 'Python Starter Project' --url http://localhost:8000 -g solo --browser
 ```
 
 ## Next Steps
-
 Continue with the [Battlesnake Quickstart Guide](https://docs.battlesnake.com/quickstart) to customize and improve your Battlesnake's behavior.
 
 ## Included Competitive Snake
@@ -62,13 +55,11 @@ This repo now includes `snakes/BestBattleSnake.py`, a stronger default snake tha
 - tail access checks for better long-term survival
 
 Run it explicitly with:
-
 ```sh
 SNAKE=BestBattleSnake python main.py
 ```
 
 Optional duel tuning (when only 2 snakes are alive):
-
 ```sh
 BATTLE_SNAKE_DUEL_STYLE=balanced python main.py
 ```