Fix build and run issues

internal/db/db.go

@@ -3,9 +3,10 @@ package db
 import (
 	"context"
 	"database/sql"
+	"errors"
 	"fmt"
 
-	_ "github.com/go-sql-driver/mysql"
+	"github.com/go-sql-driver/mysql"
 )
 
 func Open(dsn string) (*sql.DB, error) {
@@ -22,6 +23,10 @@ func Open(dsn string) (*sql.DB, error) {
 func Migrate(ctx context.Context, db *sql.DB) error {
 	for _, stmt := range statements {
 		if _, err := db.ExecContext(ctx, stmt); err != nil {
+			var mysqlErr *mysql.MySQLError
+			if errors.As(err, &mysqlErr) && mysqlErr.Number == 1060 {
+				continue // duplicate column — already exists
+			}
 			return fmt.Errorf("migrate: %w", err)
 		}
 	}

internal/db/schema.go

@@ -10,7 +10,7 @@ var statements = []string{
     active                  TINYINT NOT NULL DEFAULT 1,
     is_trainee              TINYINT NOT NULL DEFAULT 0,
     phone                   VARCHAR(20) NULL,
-    operational_roles       TEXT NOT NULL DEFAULT '',
+    operational_roles       TEXT NOT NULL,
     notification_preference VARCHAR(50) NOT NULL DEFAULT 'email',
     admin_notes             TEXT NULL,
     last_login              DATETIME NULL,
@@ -19,15 +19,15 @@ var statements = []string{
     created_at              TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
     updated_at              TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci`,
-	// Additive column migrations for existing deployments
-	`ALTER TABLE volunteers ADD COLUMN IF NOT EXISTS is_trainee TINYINT NOT NULL DEFAULT 0`,
-	`ALTER TABLE volunteers ADD COLUMN IF NOT EXISTS phone VARCHAR(20) NULL`,
-	`ALTER TABLE volunteers ADD COLUMN IF NOT EXISTS operational_roles TEXT NOT NULL DEFAULT ''`,
-	`ALTER TABLE volunteers ADD COLUMN IF NOT EXISTS notification_preference VARCHAR(50) NOT NULL DEFAULT 'email'`,
-	`ALTER TABLE volunteers ADD COLUMN IF NOT EXISTS admin_notes TEXT NULL`,
-	`ALTER TABLE volunteers ADD COLUMN IF NOT EXISTS last_login DATETIME NULL`,
-	`ALTER TABLE volunteers ADD COLUMN IF NOT EXISTS invite_token VARCHAR(255) NULL`,
-	`ALTER TABLE volunteers ADD COLUMN IF NOT EXISTS invite_expires_at DATETIME NULL`,
+	// Additive column migrations for existing deployments (duplicates ignored at runtime)
+	`ALTER TABLE volunteers ADD COLUMN is_trainee TINYINT NOT NULL DEFAULT 0`,
+	`ALTER TABLE volunteers ADD COLUMN phone VARCHAR(20) NULL`,
+	`ALTER TABLE volunteers ADD COLUMN operational_roles TEXT NOT NULL`,
+	`ALTER TABLE volunteers ADD COLUMN notification_preference VARCHAR(50) NOT NULL DEFAULT 'email'`,
+	`ALTER TABLE volunteers ADD COLUMN admin_notes TEXT NULL`,
+	`ALTER TABLE volunteers ADD COLUMN last_login DATETIME NULL`,
+	`ALTER TABLE volunteers ADD COLUMN invite_token VARCHAR(255) NULL`,
+	`ALTER TABLE volunteers ADD COLUMN invite_expires_at DATETIME NULL`,
 	`CREATE TABLE IF NOT EXISTS schedules (
     id            INT AUTO_INCREMENT PRIMARY KEY,
     volunteer_id  INT NOT NULL,
@@ -72,11 +72,11 @@ var statements = []string{
     id            INT AUTO_INCREMENT PRIMARY KEY,
     volunteer_id  INT NOT NULL,
     message       TEXT NOT NULL,
-    read          TINYINT NOT NULL DEFAULT 0,
+    is_read       TINYINT NOT NULL DEFAULT 0,
     created_at    TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
     FOREIGN KEY (volunteer_id) REFERENCES volunteers(id) ON DELETE CASCADE,
     INDEX idx_volunteer_id (volunteer_id),
-    INDEX idx_read (read)
+    INDEX idx_is_read (is_read)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci`,
 	`CREATE TABLE IF NOT EXISTS shift_templates (
     id           INT AUTO_INCREMENT PRIMARY KEY,