Fix BASE_URL config loading, add tasks/projects; robust .env path resolution

- Config: try ENV_FILE, .env, ../.env for loading; trim trailing slash from BaseURL
- Log BASE_URL at server startup for verification
- .env.example: document BASE_URL
- Tasks, projects, tags, migrations and related API/handlers

Made-with: Cursor

internal/utils/validation.go

@@ -95,3 +95,37 @@ func ValidateRecurrenceRangeLimit(start, end time.Time) error {
 	}
 	return nil
 }
+
+func ValidateTaskTitle(title string) error {
+	if len(title) < 1 || len(title) > 500 {
+		return models.NewValidationError("task title must be 1-500 characters")
+	}
+	return nil
+}
+
+func ValidateTaskStatus(status string) error {
+	valid := map[string]bool{"todo": true, "in_progress": true, "done": true, "archived": true}
+	if !valid[status] {
+		return models.NewValidationError("invalid task status")
+	}
+	return nil
+}
+
+func ParseTime(s string) (time.Time, error) {
+	t, err := time.Parse(time.RFC3339, s)
+	if err != nil {
+		t, err = time.Parse("2006-01-02T15:04:05Z07:00", s)
+	}
+	if err != nil {
+		t, err = time.Parse("2006-01-02", s)
+	}
+	return t, err
+}
+
+func ValidateTaskPriority(priority string) error {
+	valid := map[string]bool{"low": true, "medium": true, "high": true, "critical": true}
+	if !valid[priority] {
+		return models.NewValidationError("invalid task priority")
+	}
+	return nil
+}