feat: add Phase 4 AI tools with Python bridge and 6 new tools

Add Python bridge (packages/ai/src/bridge.ts) that calls Python scripts
via child_process with venv-first fallback to system python3. Implements
6 AI-powered tools:

- Remove Background: rembg-based with U2-Net/IS-Net models
- Image Upscaling: Real-ESRGAN with Lanczos fallback
- OCR/Text Extraction: Tesseract + PaddleOCR engines
- Face/PII Blur: MediaPipe face detection with configurable blur
- Object Eraser: LaMa inpainting with mask-based input
- Smart Crop: Sharp attention-based entropy cropping (no Python needed)

Each tool includes: Python script, TypeScript wrapper, API route,
and React settings component. All Python scripts handle ImportError
gracefully with clear installation messages.

packages/ai/python/upscale.py

@@ -0,0 +1,78 @@
+"""Image upscaling with Real-ESRGAN fallback to Lanczos."""
+import sys
+import json
+
+
+def main():
+    input_path = sys.argv[1]
+    output_path = sys.argv[2]
+    settings = json.loads(sys.argv[3]) if len(sys.argv) > 3 else {}
+
+    scale = settings.get("scale", 2)
+
+    try:
+        from PIL import Image
+
+        img = Image.open(input_path)
+        new_size = (img.width * scale, img.height * scale)
+
+        # Try Real-ESRGAN first
+        try:
+            from basicsr.archs.rrdbnet_arch import RRDBNet
+            from realesrgan import RealESRGANer
+            import numpy as np
+
+            model = RRDBNet(
+                num_in_ch=3,
+                num_out_ch=3,
+                num_feat=64,
+                num_block=23,
+                num_grow_ch=32,
+                scale=scale,
+            )
+            upsampler = RealESRGANer(
+                scale=scale,
+                model_path=None,
+                model=model,
+                half=False,
+            )
+            img_array = np.array(img.convert("RGB"))
+            output, _ = upsampler.enhance(img_array, outscale=scale)
+            result = Image.fromarray(output)
+            result.save(output_path)
+            method = "realesrgan"
+        except (ImportError, Exception):
+            # Fallback to Lanczos upscaling
+            img_upscaled = img.resize(new_size, Image.LANCZOS)
+            img_upscaled.save(output_path)
+            method = "lanczos"
+
+        print(
+            json.dumps(
+                {
+                    "success": True,
+                    "scale": scale,
+                    "width": new_size[0],
+                    "height": new_size[1],
+                    "method": method,
+                }
+            )
+        )
+
+    except ImportError:
+        print(
+            json.dumps(
+                {
+                    "success": False,
+                    "error": "Pillow is not installed. Install with: pip install Pillow",
+                }
+            )
+        )
+        sys.exit(1)
+    except Exception as e:
+        print(json.dumps({"success": False, "error": str(e)}))
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()