feat: define all 8 SQLModel tables

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/models/exercise.py

@@ -0,0 +1,35 @@
+"""Exercise model for the exercise library catalog.
+
+Each exercise belongs to a workout day and includes form cues.
+"""
+
+from datetime import datetime
+from typing import Optional
+
+from sqlmodel import Field, SQLModel
+
+
+class Exercise(SQLModel, table=True):
+    """An exercise in the workout library.
+
+    Attributes:
+        id: Primary key, auto-incremented.
+        name: Exercise name (e.g., "DB Chest Press (Floor)").
+        muscle_group: Target muscle group (e.g., "Chest", "Shoulders").
+        workout_day: Which day this exercise belongs to (Push/Pull/Lower/Full Body).
+        sets: Default number of sets.
+        tempo: Tempo notation (e.g., "3-1-2" = 3s eccentric, 1s pause, 2s concentric).
+        form_cues: Detailed form instructions.
+        created_at: Timestamp when the record was created.
+    """
+
+    __tablename__ = "exercises"
+
+    id: Optional[int] = Field(default=None, primary_key=True)
+    name: str = Field(index=True)
+    muscle_group: str = Field(default="")
+    workout_day: str = Field(index=True)
+    sets: int = Field(default=3)
+    tempo: str = Field(default="")
+    form_cues: str = Field(default="")
+    created_at: datetime = Field(default_factory=datetime.utcnow)