chore: initialize backend project config

.env.example

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+SERVICE_NAME="BitCheck Image Verification API"
+MAX_UPLOAD_BYTES=12582912
+MODEL_PATH="models/image_detector.pth"
+MODEL_ARCH="efficientnet_b0"
+LOG_LEVEL="INFO"

.gitattributes

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+*.keras filter=lfs diff=lfs merge=lfs -text
+*.pth filter=lfs diff=lfs merge=lfs -text
+*.pt filter=lfs diff=lfs merge=lfs -text
+*.h5 filter=lfs diff=lfs merge=lfs -text

.gitignore

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+.venv/
+venv/
+__pycache__/
+*.py[cod]
+.env
+
+uploads/*
+!uploads/.gitkeep
+
+outputs/*
+!outputs/.gitkeep

models/README.md

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+# BitCheck Models
+
+Place a fine-tuned PyTorch binary image detector at:
+
+```text
+models/image_detector.pth
+```
+
+The current backend expects an EfficientNet-B0 architecture with a two-class classifier:
+
+- class 0: real/authentic
+- class 1: AI-generated/synthetic
+
+If this file is missing, BitCheck starts in `untrained_placeholder` mode. The rest of the verification pipeline still runs, but model probabilities are marked as unreliable in the API response.

outputs/.gitkeep

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+

pyproject.toml

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+[project]
+name = "bitcheck-ai-backend"
+version = "0.1.0"
+description = "BitCheck image verification backend"
+requires-python = ">=3.10"
+dependencies = [
+  "fastapi>=0.115.0",
+  "uvicorn[standard]>=0.30.0",
+  "python-multipart>=0.0.9",
+  "pydantic>=2.7.0",
+  "pydantic-settings>=2.3.0",
+  "torch>=2.2.0",
+  "torchvision>=0.17.0",
+  "Pillow>=10.3.0",
+  "opencv-python-headless>=4.9.0.80",
+  "numpy>=1.26.0",
+  "pytesseract>=0.3.10",
+]
+
+[tool.uv]
+package = false
+
+[tool.uv.sources]
+torch = { index = "pytorch-cpu" }
+torchvision = { index = "pytorch-cpu" }
+
+[[tool.uv.index]]
+name = "pytorch-cpu"
+url = "https://download.pytorch.org/whl/cpu"
+explicit = true

requirements.txt

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+--index-url https://download.pytorch.org/whl/cpu
+--extra-index-url https://pypi.org/simple
+
+fastapi>=0.115.0
+uvicorn[standard]>=0.30.0
+python-multipart>=0.0.9
+pydantic>=2.7.0
+pydantic-settings>=2.3.0
+torch>=2.2.0
+torchvision>=0.17.0
+Pillow>=10.3.0
+opencv-python-headless>=4.9.0.80
+numpy>=1.26.0
+pytesseract>=0.3.10

uploads/.gitkeep

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+