feat: add Alembic migrations with initial 8-table schema

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

alembic/env.py

@@ -0,0 +1,57 @@
+"""Alembic environment configuration.
+
+Imports all SQLModel models so autogenerate detects schema changes.
+"""
+
+from logging.config import fileConfig
+
+from alembic import context
+from sqlalchemy import engine_from_config, pool
+from sqlmodel import SQLModel
+
+# Import all models so SQLModel.metadata knows about them
+from app.models import (  # noqa: F401
+    User, Exercise, Warmup, WorkoutDay,
+    UserExerciseProgram, WorkoutSession, WorkoutLog, ProgressLog,
+)
+
+config = context.config
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+target_metadata = SQLModel.metadata
+
+
+def run_migrations_offline() -> None:
+    """Run migrations in 'offline' mode (SQL script generation)."""
+    url = config.get_main_option("sqlalchemy.url")
+    context.configure(
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online() -> None:
+    """Run migrations in 'online' mode (direct DB connection)."""
+    connectable = engine_from_config(
+        config.get_section(config.config_ini_section, {}),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+    with connectable.connect() as connection:
+        context.configure(
+            connection=connection,
+            target_metadata=target_metadata,
+        )
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()