Feat: Move key.txt to auth_profiles for easier Docker management (Fixes #216)

[NikkeTryHard]

Summary

This pull request resolves issue #216 by relocating the key.txt API key file from the project root into the auth_profiles/ directory.

The primary motivation for this change is to simplify data persistence when using Docker. It allows the entire auth_profiles directory, which contains session data and now the API keys, to be managed by a single named volume. This improves containerization and makes configuration more intuitive.

Changes Implemented

• api_utils/auth_utils.py: The KEY_FILE_PATH variable was updated to point to the new location (auth_profiles/key.txt). Logic was also added to ensure the auth_profiles directory is created automatically if it doesn't exist.
• api_utils/routes.py: The API key management endpoints (add_api_key, delete_api_key) were refactored to use the centralized KEY_FILE_PATH from auth_utils, improving code consistency.

Testing Results

The feature was thoroughly tested on Windows using PowerShell to verify its functionality.

Test 1: Initialization

• Action: Started the server without an existing key.txt.
• Result: Success. A new, empty key.txt was correctly created in auth_profiles/, and no file was created in the root directory.

Test 2: Authentication with a Valid Key

• Action: Manually added my-test-key-123 to auth_profiles/key.txt and restarted the server.
• Result: Success. The following PowerShell curl command was executed and returned a 200 OK status, confirming successful authentication.

Command:

curl -Uri 'http://localhost:2048/v1/chat/completions' `
     -Method POST `
     -ContentType 'application/json' `
     -Headers @{
         "Authorization" = "Bearer my-test-key-123"
     } `
     -Body '{"model": "gemini-2.5-pro", "messages": [{"role": "user", "content": "Hello, this is a successful auth test."}]}'

[CJackHwang]

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