docs: add example.env and document all environment variables

- Create example.env with all 31 environment variables documented
- Update docker-compose.yml to use env_file directive
- Update doc/deployment.md with Quick Start and missing variables
- Add OXICLOUD_BASE_URL and WOPI configuration docs
- Update README.md Docker section with .env setup
- Remove duplicate port mapping (incorporates 4577e56)
- Fix server port default from 8085 to 8086

README.md

@@ -46,11 +46,15 @@ cargo run --bin migrate --features migrations
 cargo run --release
 ```
 
-Open `http://localhost:8085` in your browser.
+Open `http://localhost:8086` in your browser.
 
 ### Docker (alternative)
 
 ```bash
+# Copy example environment file and customize
+cp example.env .env
+# Edit .env with your settings (optional - defaults work for quick testing)
+
 docker compose up -d
 ```