Refactor environment and configuration management

- Updated the project structure to store configuration files (.env, models.yaml, extensions.yaml) in the project root instead of the user's home directory.
- Enhanced the setup process to automatically copy example files to the project root on first run.
- Implemented a migration function to transfer legacy configuration files from the user's home directory to the new project structure.
- Revised documentation to reflect changes in file locations and setup instructions.
- Improved code readability and maintainability by refactoring path management functions.

models.example.yaml

@@ -1,13 +1,19 @@
-# Copy to ~/.gpu-rent/models.yaml
+# Copy to models.yaml in this repo (never commit the working copy).
 # version_id = modelVersionId from the URL (not the model id).
 # url may be civitai.com or civitai.red — both work.
 # Requires CIVITAI_API_TOKEN. Empty file → SwarmUI default model.
 
 checkpoint:
-  - version_id: 0
-  # - url: https://civitai.red/models/123?modelVersionId=456
+  # Realism by Stable Yogi — Krea 2
+  - url: https://civitai.red/models/2786499/realism-by-stable-yogi-krea2?modelVersionId=3231611
+
 lora:
-  - version_id: 0
+  # Realistic Snapshot — Z-Image Turbo / Krea 2
+  - url: https://civitai.red/models/2268008/realistic-snapshot-z-image-turbo-krea-2?modelVersionId=3084537
+  # Cutifyier
+  - url: https://civitai.red/models/2187487/cutifyier?modelVersionId=3107521
+  # 2000s Analog Core
+  - url: https://civitai.red/models/1134895/2000s-analog-core?modelVersionId=3103914
 
 # vae:
 #   - version_id: 0