feat: add Pomodoro timer functionality with logging and project goals

- Implemented Pomodoro timer in the app, allowing users to start, pause, and stop sessions.
- Added context for managing Pomodoro state and actions.
- Integrated time logging for completed sessions to track productivity.
- Enhanced project settings to include time goals and Pomodoro settings.
- Created migration scripts to update the database schema for new project fields and time logs.
- Updated UI components to display Pomodoro controls and project time summaries.
- Added category filtering for projects in the project list view.

backend/app/models.py

@@ -16,6 +16,11 @@ class Project(Base):
     description = Column(Text, nullable=True)
     statuses = Column(JSON, nullable=False, default=DEFAULT_STATUSES)
     is_archived = Column(Boolean, default=False, nullable=False)
+    category = Column(String(100), nullable=True)
+    weekly_hours_goal = Column(Integer, nullable=True)   # stored in minutes
+    total_hours_goal = Column(Integer, nullable=True)    # stored in minutes
+    pomodoro_work_minutes = Column(Integer, nullable=True, default=25)
+    pomodoro_break_minutes = Column(Integer, nullable=True, default=5)
     created_at = Column(DateTime, default=datetime.utcnow)
     updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)
 
@@ -40,3 +45,17 @@ class Task(Base):
 
     project = relationship("Project", back_populates="tasks")
     parent = relationship("Task", remote_side=[id], backref="subtasks")
+    time_logs = relationship("TimeLog", back_populates="task", cascade="all, delete-orphan")
+
+
+class TimeLog(Base):
+    __tablename__ = "time_logs"
+
+    id = Column(Integer, primary_key=True, index=True)
+    task_id = Column(Integer, ForeignKey("tasks.id"), nullable=False)
+    minutes = Column(Integer, nullable=False)
+    note = Column(Text, nullable=True)
+    session_type = Column(String(50), default="manual")  # 'pomodoro' | 'manual'
+    logged_at = Column(DateTime, default=datetime.utcnow)
+
+    task = relationship("Task", back_populates="time_logs")