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/ocr.py

@@ -0,0 +1,81 @@
+"""Text extraction from images using Tesseract or PaddleOCR."""
+import sys
+import json
+
+
+def main():
+    input_path = sys.argv[1]
+    settings = json.loads(sys.argv[2]) if len(sys.argv) > 2 else {}
+
+    engine = settings.get("engine", "tesseract")
+    language = settings.get("language", "en")
+
+    try:
+        if engine == "paddleocr":
+            try:
+                from paddleocr import PaddleOCR
+
+                ocr = PaddleOCR(use_angle_cls=True, lang=language)
+                result = ocr.ocr(input_path, cls=True)
+                text = "\n".join(
+                    [
+                        line[1][0]
+                        for res in result
+                        if res
+                        for line in res
+                        if line and line[1]
+                    ]
+                )
+                print(
+                    json.dumps({"success": True, "text": text, "engine": "paddleocr"})
+                )
+            except ImportError:
+                print(
+                    json.dumps(
+                        {
+                            "success": False,
+                            "error": "PaddleOCR is not installed. Install with: pip install paddleocr paddlepaddle",
+                        }
+                    )
+                )
+                sys.exit(1)
+        else:
+            # Tesseract via subprocess
+            import subprocess
+
+            lang_map = {"en": "eng", "de": "deu", "fr": "fra", "es": "spa", "zh": "chi_sim", "ja": "jpn", "ko": "kor"}
+            tess_lang = lang_map.get(language, "eng")
+
+            try:
+                result = subprocess.run(
+                    ["tesseract", input_path, "stdout", "-l", tess_lang],
+                    capture_output=True,
+                    text=True,
+                    timeout=120,
+                )
+                text = result.stdout.strip()
+                if result.returncode != 0 and not text:
+                    raise RuntimeError(result.stderr.strip() or "Tesseract failed")
+                print(
+                    json.dumps(
+                        {"success": True, "text": text, "engine": "tesseract"}
+                    )
+                )
+            except FileNotFoundError:
+                print(
+                    json.dumps(
+                        {
+                            "success": False,
+                            "error": "Tesseract is not installed. Install with: apt-get install tesseract-ocr",
+                        }
+                    )
+                )
+                sys.exit(1)
+
+    except Exception as e:
+        print(json.dumps({"success": False, "error": str(e)}))
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()