remove legacy migration conversion code

Pre-1.0 software with no installed base — no need to handle
converting from old TEXT-based schema_migrations format.

Removed: convertLegacyMigrations, ensureBootstrapVersion,
readLegacyVersions, rebuildMigrationsTable, and
TestApplyMigrationsLegacyConversion.

Simplified bootstrapMigrationsTable to only check existence
and run 000_migration.sql if missing.

internal/database/migrations_test.go

@@ -115,78 +115,3 @@ func TestApplyMigrationsIdempotent(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, 8, count)
 }
-
-func TestApplyMigrationsLegacyConversion(t *testing.T) {
-	t.Parallel()
-
-	db, err := sql.Open("sqlite3", ":memory:?_foreign_keys=on")
-	require.NoError(t, err)
-
-	defer func() { _ = db.Close() }()
-
-	ctx := context.Background()
-
-	// Simulate the old TEXT-based schema_migrations table.
-	_, err = db.ExecContext(ctx, `
-		CREATE TABLE schema_migrations (
-			version TEXT PRIMARY KEY,
-			applied_at DATETIME DEFAULT CURRENT_TIMESTAMP
-		)
-	`)
-	require.NoError(t, err)
-
-	// Insert legacy filename-based versions (as if migrations 001-007 were applied).
-	legacyVersions := []string{
-		"001_initial.sql",
-		"002_remove_container_id.sql",
-		"003_add_ports.sql",
-		"004_add_commit_url.sql",
-		"005_add_webhook_secret_hash.sql",
-		"006_add_previous_image_id.sql",
-		"007_add_resource_limits.sql",
-	}
-
-	for _, v := range legacyVersions {
-		_, err = db.ExecContext(ctx,
-			"INSERT INTO schema_migrations (version) VALUES (?)", v)
-		require.NoError(t, err)
-	}
-
-	// Also create the application tables that would exist on a real database
-	// so that the migrations (001-007) don't fail when re-applied.
-	// Actually, since the legacy versions will be converted and recognized
-	// as already-applied, the DDL migrations won't re-run. We just need
-	// to make sure ApplyMigrations succeeds.
-
-	// Run ApplyMigrations — this should convert legacy versions and
-	// skip all already-applied migrations.
-	err = database.ApplyMigrations(ctx, db, nil)
-	require.NoError(t, err)
-
-	// Verify version 0 is now present (from bootstrap).
-	var zeroVersion int
-
-	err = db.QueryRowContext(ctx,
-		"SELECT version FROM schema_migrations WHERE version = 0",
-	).Scan(&zeroVersion)
-	require.NoError(t, err)
-	assert.Equal(t, 0, zeroVersion)
-
-	// Verify all 8 versions are present (0 through 7).
-	var count int
-
-	err = db.QueryRowContext(ctx,
-		"SELECT COUNT(*) FROM schema_migrations",
-	).Scan(&count)
-	require.NoError(t, err)
-	assert.Equal(t, 8, count)
-
-	// Verify versions are stored as integers, not text filenames.
-	var maxVersion int
-
-	err = db.QueryRowContext(ctx,
-		"SELECT MAX(version) FROM schema_migrations",
-	).Scan(&maxVersion)
-	require.NoError(t, err)
-	assert.Equal(t, 7, maxVersion)
-}