fix: headless/Colab mode + UI reliability fixes

Critical fixes for Colab no-UI mode:
- configs/config.py: Lazy imports for onnxruntime + GPU backends,
  fixed singleton pattern, removed eager deps that crashed headless
- utils/variables.py: get_config() now uses local lazy Config class
  instead of the eager configs.config.Config
- app/__init__.py: Lazy imports for gui/tensorboard so importing
  the app module doesn't crash without gradio
- engine/realtime/audio.py: Wrapped sounddevice + librosa in
  try/except with None guards for headless environments
- Created utils/feedback.py: Lightweight logging-only gr_info/
  gr_warning/gr_error + utility functions (process_output,
  replace_punctuation, replace_url, etc.) that work without UI deps

UI fixes:
- ui/feedback.py: Replaced raw gr.update() calls with safe dict
  pattern to prevent AttributeError when gradio is unavailable
- services/*.py: Split imports - gr_info/gr_warning/gr_error now
  from utils.feedback (no UI dep), UI-specific functions from ui.feedback
- engine/inference/inference.py: Split imports similarly
- engine/training/extract/preparing_files.py: Fixed wrong import
  source (ui.feedback → utils.variables for config/configs)

Other fixes:
- models/backends/directml.py: Lazy import of fairseq (was eager)
- services/realtime_client.py: Wrapped FastAPI import in try/except
- Removed 90+ sys.path.append(os.getcwd()) code smells across
  entire codebase - unnecessary in proper package

Author: BF667

advanced_rvc_inference/api/cli_complete.py

@@ -12,7 +12,6 @@
 import os
 import sys
 
-sys.path.append(os.getcwd())
 
 try:
     argv = sys.argv[1]

advanced_rvc_inference/app/__init__.py

@@ -5,8 +5,17 @@
 # Import heavy GUI dependencies lazily so headless / CLI-only usage
 # (e.g. Colab no-UI notebook, rvc-cli commands) is not blocked.
 
-from .gui import launch as launch_gui
-from .run_tensorboard import launch_tensorboard
+
+def launch_gui(*args, **kwargs):
+    """Launch the Gradio web interface (lazy import)."""
+    from .gui import launch
+    return launch(*args, **kwargs)
+
+
+def launch_tensorboard(*args, **kwargs):
+    """Launch TensorBoard (lazy import)."""
+    from .run_tensorboard import launch_tensorboard as _launch
+    return _launch(*args, **kwargs)
 
 
 __all__ = ['launch_gui', 'launch_tensorboard']

advanced_rvc_inference/app/run_tensorboard.py

@@ -7,7 +7,6 @@
 
 from tensorboard import program
 
-sys.path.append(os.getcwd())
 
 from advanced_rvc_inference.utils.variables import config, translations, logger
 

advanced_rvc_inference/app/tabs/downloads/downloads.py

@@ -3,7 +3,6 @@
 
 import gradio as gr
 
-sys.path.append(os.getcwd())
 
 from advanced_rvc_inference.utils.variables import (
     models, 

advanced_rvc_inference/app/tabs/extra/child/convert_model.py

@@ -3,7 +3,6 @@
 
 import gradio as gr
 
-sys.path.append(os.getcwd())
 
 from advanced_rvc_inference.ui.feedback import visible, shutil_move
 from advanced_rvc_inference.services.model_utils import onnx_export

advanced_rvc_inference/app/tabs/extra/child/create_srt.py

@@ -3,7 +3,6 @@
 
 import gradio as gr
 
-sys.path.append(os.getcwd())
 
 from advanced_rvc_inference.services.csrt import create_srt
 from advanced_rvc_inference.ui.feedback import shutil_move, change_audios_choices

advanced_rvc_inference/app/tabs/extra/child/f0_extract.py

@@ -3,7 +3,6 @@
 
 import gradio as gr
 
-sys.path.append(os.getcwd())
 
 from advanced_rvc_inference.services.f0_extract import f0_extract
 from advanced_rvc_inference.ui.feedback import change_audios_choices, unlock_f0, shutil_move

advanced_rvc_inference/app/tabs/extra/child/fushion.py

@@ -3,7 +3,6 @@
 
 import gradio as gr
 
-sys.path.append(os.getcwd())
 
 from advanced_rvc_inference.ui.feedback import visible, shutil_move
 from advanced_rvc_inference.services.model_utils import fushion_model

advanced_rvc_inference/app/tabs/extra/child/read_model.py

@@ -3,7 +3,6 @@
 
 import gradio as gr
 
-sys.path.append(os.getcwd())
 
 from advanced_rvc_inference.ui.feedback import shutil_move
 from advanced_rvc_inference.services.model_utils import model_info

advanced_rvc_inference/app/tabs/extra/child/settings.py

@@ -3,7 +3,6 @@
 
 import gradio as gr
 
-sys.path.append(os.getcwd())
 
 from advanced_rvc_inference.ui.feedback import change_fp
 from advanced_rvc_inference.services.utils import stop_pid