Enhance Docker support and configuration

- Updated .env.example to recommend using docker.env and secrets for sensitive data.
- Modified .gitignore to include docker.env and secrets directory.
- Adjusted docker-compose.yml to utilize environment files and updated port mappings.
- Implemented read_env_or_file utility for better environment variable management.
- Refactored portfolio and trades routers to use the new utility for fetching environment variables.
- Added integration and phase 2 test updates for new environment variable handling.
- Created new documentation for Docker operations and secret management.
- Added placeholder files for Docker secrets and configuration.

secrets/README.md

@@ -0,0 +1,20 @@
+# Docker Secret Files
+
+Create local secret files in this directory before starting the Docker stack.
+
+Required:
+- `tws_password`
+- `webhook_secret`
+
+Optional:
+- `vnc_password`
+- `ui_username`
+- `ui_password`
+
+Example:
+
+```bash
+printf '%s\n' 'your_ibkr_password' > secrets/tws_password
+printf '%s\n' 'change_this_webhook_secret' > secrets/webhook_secret
+chmod 600 secrets/tws_password secrets/webhook_secret
+```