Implement complete AI Photo Edit tool with mask-scoped regeneration

This commit implements a full-stack AI photo editing application that
allows users to regenerate only selected areas of images using AI.

Features implemented:
- Frontend (React + Fabric.js):
  * Interactive canvas with selection tools (rectangle, ellipse, lasso)
  * Real-time selection preview and editing
  * Mode toggle (A: patch only, B: patch + context)
  * Feather slider for edge blending (0-50px)
  * Prompt input for AI instructions
  * Edit history viewer with revert capability
  * Responsive UI with dark theme

- Backend (FastAPI):
  * RESTful API for projects and edits
  * SQLite database for metadata storage
  * Image processing pipeline with PIL/OpenCV
  * AI provider interface (pluggable)
  * Support for OpenAI, Stability AI, and mock providers
  * Feathered alpha blending for smooth compositing
  * Complete edit history tracking
  * File-based storage for images and edits

- Image Processing:
  * Patch extraction from bounding boxes
  * Mask generation for all selection types
  * Feathered edge blending
  * Patch compositing back to full image
  * No pixels modified outside selection
  * All edits reversible

- Infrastructure:
  * Docker Compose orchestration
  * Production and development configurations
  * Nginx reverse proxy for frontend
  * Hot-reload support for development
  * Volume persistence for data

Architecture follows specification exactly:
- Only selected regions are regenerated
- Full image pixels preserved outside mask
- Two-mode operation (cost vs quality)
- Complete edit history and reversibility
- Self-hosted with external AI API calls

All components are fully functional and ready for deployment.

backend/app/routers/images.py

@@ -0,0 +1,81 @@
+from fastapi import APIRouter, HTTPException, Depends
+from fastapi.responses import FileResponse
+from sqlalchemy.orm import Session
+from pathlib import Path
+
+from app.database import get_db
+from app.models.project import Project
+from app.services.edit_service import EditService
+
+router = APIRouter(prefix="/projects", tags=["images"])
+
+
+@router.get("/{project_id}/original")
+def get_original_image(
+    project_id: int,
+    db: Session = Depends(get_db)
+):
+    """Get the original uploaded image"""
+    project = db.query(Project).filter(Project.id == project_id).first()
+    if not project:
+        raise HTTPException(status_code=404, detail="Project not found")
+
+    edit_service = EditService()
+    image_path = edit_service.get_original_image_path(project_id)
+
+    if not image_path.exists():
+        raise HTTPException(status_code=404, detail="Original image not found")
+
+    return FileResponse(
+        image_path,
+        media_type="image/png",
+        headers={"Cache-Control": "public, max-age=3600"}
+    )
+
+
+@router.get("/{project_id}/current")
+def get_current_image(
+    project_id: int,
+    db: Session = Depends(get_db)
+):
+    """Get the current edited image"""
+    project = db.query(Project).filter(Project.id == project_id).first()
+    if not project:
+        raise HTTPException(status_code=404, detail="Project not found")
+
+    edit_service = EditService()
+    image_path = edit_service.get_current_image_path(project_id)
+
+    if not image_path.exists():
+        raise HTTPException(status_code=404, detail="Current image not found")
+
+    return FileResponse(
+        image_path,
+        media_type="image/png",
+        headers={"Cache-Control": "no-cache"}
+    )
+
+
+@router.get("/{project_id}/history/{edit_id}/result")
+def get_edit_result(
+    project_id: int,
+    edit_id: int,
+    db: Session = Depends(get_db)
+):
+    """Get the result image from a specific edit"""
+    project = db.query(Project).filter(Project.id == project_id).first()
+    if not project:
+        raise HTTPException(status_code=404, detail="Project not found")
+
+    edit_service = EditService()
+    edit_dir = edit_service.get_edit_dir(project_id, edit_id)
+    result_path = edit_dir / "result.png"
+
+    if not result_path.exists():
+        raise HTTPException(status_code=404, detail="Edit result not found")
+
+    return FileResponse(
+        result_path,
+        media_type="image/png",
+        headers={"Cache-Control": "public, max-age=3600"}
+    )