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/models/__init__.py

@@ -0,0 +1,5 @@
+from app.models.user import User
+from app.models.project import Project
+from app.models.edit import Edit
+
+__all__ = ["User", "Project", "Edit"]

backend/app/models/edit.py

@@ -0,0 +1,23 @@
+from sqlalchemy import Column, Integer, String, DateTime, ForeignKey, Text
+from sqlalchemy.orm import relationship
+from datetime import datetime
+from app.database import Base
+
+
+class Edit(Base):
+    __tablename__ = "edits"
+
+    id = Column(Integer, primary_key=True, index=True)
+    project_id = Column(Integer, ForeignKey("projects.id"), nullable=False)
+    created_at = Column(DateTime, default=datetime.utcnow)
+    mode = Column(String, nullable=False)  # "A" or "B"
+    prompt = Column(Text, nullable=False)
+    selection_type = Column(String, nullable=False)  # "rectangle", "ellipse", "lasso"
+    bbox_json = Column(Text, nullable=False)  # JSON string of {x, y, width, height}
+    feather_px = Column(Integer, default=0)
+    ai_provider = Column(String, nullable=False)
+    status = Column(String, nullable=False)  # "pending", "processing", "completed", "failed"
+    error_message = Column(Text, nullable=True)
+
+    # Relationships
+    project = relationship("Project", back_populates="edits")

backend/app/models/project.py

@@ -0,0 +1,18 @@
+from sqlalchemy import Column, Integer, String, DateTime, ForeignKey
+from sqlalchemy.orm import relationship
+from datetime import datetime
+from app.database import Base
+
+
+class Project(Base):
+    __tablename__ = "projects"
+
+    id = Column(Integer, primary_key=True, index=True)
+    user_id = Column(Integer, ForeignKey("users.id"), nullable=False)
+    name = Column(String, nullable=False)
+    created_at = Column(DateTime, default=datetime.utcnow)
+    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
+
+    # Relationships
+    user = relationship("User", back_populates="projects")
+    edits = relationship("Edit", back_populates="project", cascade="all, delete-orphan")

backend/app/models/user.py

@@ -0,0 +1,16 @@
+from sqlalchemy import Column, Integer, String, DateTime
+from sqlalchemy.orm import relationship
+from datetime import datetime
+from app.database import Base
+
+
+class User(Base):
+    __tablename__ = "users"
+
+    id = Column(Integer, primary_key=True, index=True)
+    email = Column(String, unique=True, index=True, nullable=False)
+    password_hash = Column(String, nullable=False)
+    created_at = Column(DateTime, default=datetime.utcnow)
+
+    # Relationships
+    projects = relationship("Project", back_populates="user", cascade="all, delete-orphan")