Adds contributing guide and changelog

Adds a contributing guide with instructions for setting up a local development environment using Docker.

Also creates a changelog to track notable changes.

### Added
- Contributing guide for local development setup.
- Changelog file.

.gitignore

@@ -10,3 +10,4 @@ __pycache__/
 
 # Docker crap
 *.log
+docker-compose.override.yml

CHANGELOG.md

@@ -0,0 +1,22 @@
+# Changelog
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [0.3.0] - 2025-10-08
+### Added
+- Fallback to play iTunes previews when a YouTube API key is unavailable.
+
+## [0.2.0] - 2025-10-07
+### Added
+- Full user management and authentication workflow.
+- Super-admin bootstrap settings.
+
+## [0.1.0] - 2025-10-06
+### Added
+- Revamped user interface with progress spinners and a “Load more” button.
+- YouTube-based audio prehear support.
+
+### Removed
+- Spotify integration.

CONTRIBUTING.md

@@ -0,0 +1,35 @@
+# Contributing
+
+1. Clone the repository.
+2. Checkout the `develop` branch: `git checkout develop`.
+3. **Create** a `docker-compose.override.yml` with the following contents:
+   ```yaml
+   services:
+     sonobarr:
+       build:
+         context: .
+         dockerfile: Dockerfile
+         network: host
+       image: sonobarr-local
+       volumes:
+         - ./config:/sonobarr/config
+         - /etc/localtime:/etc/localtime:ro
+         - ./src:/sonobarr/src
+       #ports:
+       #  - "5000:5000"
+       networks:
+         npm_proxy:
+           ipv4_address: 192.168.97.23 #change as you need
+
+   networks:
+     npm_proxy:
+       external: true
+   ```
+4. Build the image with `sudo docker compose up -d` - later this will re-use the local image.
+5. Make code changes in `src/` or other required files.
+6. Test the changes by restarting the docker image `sudo docker compose down && sudo docker compose up -d` and clearing cache in browser.
+7. Once ready to commit, make sure the build still works as well `sudo docker compose down -v --remove-orphans && sudo docker system prune -a --volumes -f && sudo docker compose up -d`.
+8. Commit your work to the `develop` branch.
+
+**Always test your changes with at least two accounts - admin and a common user - in the app, in at least two distinct browser builds (such as safari and chrome, for example).**
+**Remember that if you made changes affecting config (that is, database or configuration) you have to delete the `./config` folder before rebuilding or restarting the app.