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.

main.py

@@ -12,6 +12,7 @@ from fastapi.responses import JSONResponse, Response
 from fastapi.staticfiles import StaticFiles
 from ib_async import IB
 
+from config_utils import read_env_or_file
 import dependencies
 from init_db import ensure_database
 from routers import charts, health, portfolio, scanner, trades
@@ -29,8 +30,8 @@ IBKR_PORT = int(os.getenv("IBKR_PORT", 7497))
 IBKR_CLIENT_ID = int(os.getenv("IBKR_CLIENT_ID", 1))
 DB_PATH = os.getenv("DB_PATH", "trades.db")
 
-UI_USERNAME = os.getenv("UI_USERNAME", "")
-UI_PASSWORD = os.getenv("UI_PASSWORD", "")
+UI_USERNAME = read_env_or_file("UI_USERNAME", "") or ""
+UI_PASSWORD = read_env_or_file("UI_PASSWORD", "") or ""
 AUTH_ENABLED = bool(UI_USERNAME and UI_PASSWORD)
 
 _DEFAULT_SECRET = "your_super_secret_string_123"
@@ -48,7 +49,7 @@ ib = IB()
 
 
 def _validate_config() -> None:
-    webhook_secret = os.getenv("WEBHOOK_SECRET", "")
+    webhook_secret = read_env_or_file("WEBHOOK_SECRET", "") or ""
     if not webhook_secret or webhook_secret == _DEFAULT_SECRET:
         logger.warning(
             "SECURITY: WEBHOOK_SECRET is unset or still the default value. "
@@ -58,7 +59,7 @@ def _validate_config() -> None:
         logger.info("UI Basic Auth is ENABLED")
     else:
         logger.info(
-            "UI Basic Auth is DISABLED — set UI_USERNAME + UI_PASSWORD in .env to enable"
+            "UI Basic Auth is DISABLED — set UI_USERNAME/UI_PASSWORD or *_FILE to enable"
         )