Add supplements, kettlebell, calendar, push notifications, and PWA support

- Supplement tracking: CRUD endpoints, /today, /logs, Supplements page
- Kettlebell workouts: session tracking, analytics endpoint, ActiveSession page
- Calendar module: events CRUD, calendar components
- Push notifications: VAPID keys, PushSubscription model, APScheduler reminders,
  service worker with push/notificationclick handlers, Profile notifications UI
- PWA: vite-plugin-pwa, manifest, icons, service worker generation
- Frontend: TypeScript types, API modules, ConfirmModal, toast notifications
- Auth fixes: password hashing, nutrition endpoint auth
- CLAUDE.md: project documentation and development guide

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/models/kettlebell.py

@@ -0,0 +1,44 @@
+from datetime import datetime
+from typing import Optional
+
+from pydantic import BaseModel
+from sqlmodel import JSON, Field, SQLModel
+
+
+class ExerciseBlock(BaseModel):
+    order: int
+    name: str
+    description: str
+    sets: int
+    reps: int
+    duration_seconds: int  # reps=0 → timed, duration_seconds=0 → rep-based
+    weight_kg: float
+    rest_seconds: int
+    coaching_tip: str
+
+
+class KettlebellSession(SQLModel, table=True):
+    id: Optional[int] = Field(default=None, primary_key=True)
+    user_id: int = Field(foreign_key="user.id", index=True)
+    title: str
+    focus: str  # e.g. "strength", "conditioning"
+    exercises: dict = Field(default={}, sa_type=JSON)  # full AI-prescribed exercise list
+    total_duration_min: int
+    difficulty: str
+    notes: str = Field(default="")
+    status: str = Field(default="generated")  # "generated" | "in_progress" | "completed" | "abandoned"
+    started_at: Optional[datetime] = Field(default=None)
+    completed_at: Optional[datetime] = Field(default=None)
+    created_at: datetime = Field(default_factory=datetime.utcnow)
+
+
+class KettlebellSetLog(SQLModel, table=True):
+    id: Optional[int] = Field(default=None, primary_key=True)
+    session_id: int = Field(foreign_key="kettlebellsession.id", index=True)
+    exercise_order: int
+    set_number: int
+    actual_reps: int
+    actual_weight_kg: float
+    actual_duration_seconds: int
+    perceived_effort: int  # 1–10 RPE
+    completed_at: datetime = Field(default_factory=datetime.utcnow)