feat: Add loading states and improve form handling

This commit introduces several enhancements to form components and user experience across the application.

- **Sign-in Form:**
  - Implemented a loading state using `useIsMutating` from TanStack Query.
  - The username and password fields are now disabled during the login process to prevent concurrent submissions.
  - The "Sign in" button displays a spinner while the mutation is pending, providing clear visual feedback.

- **Assign to Company Modal:**
  - Refactored the modal to use `react-hook-form` for more robust state management and validation.
  - The form submission button is now disabled while the assignment request is in progress.

- **Tag Input Component:**
  - Added a new `shouldAddWithSpace` prop to allow creating tags by pressing the space bar, increasing the component's flexibility.

- **Header:**
  - Corrected the image path for the mobile header logo to display the correct icon.

src/components/forms/companies/CreateCompany.tsx

@@ -497,6 +497,7 @@ const CreateCompany = ({ defaultValues, editMode, id }: IProps) => {
             {...register("tags.cpv_codes")}
             label="CPV codes"
             name="tags.cpv_codes"
+            shouldAddWithSpace
             watch={watch}
             setValue={setValue}
             placeholder="Enter Tag CPV codes"

src/components/forms/customers/CreateCustomer.tsx

@@ -6,6 +6,7 @@ import MultiSelect from "@/components/FormElements/MultiSelect";
 import { Select } from "@/components/FormElements/select";
 import { ShowcaseSection } from "@/components/Layouts/showcase-section";
 import FormFooter from "@/components/ui/FormFooter";
+import { USERNAME_REGEX } from "@/constants/regex";
 import { FormErrorMessages } from "@/constants/Texts";
 import { CreateCustomerCredentials } from "@/lib/api";
 import useCreateCustomerPresenter from "./useCreateCustomerPresenter";
@@ -36,7 +37,7 @@ const CreateCustomer = ({ defaultValues, editMode, id }: IProps) => {
                 message: FormErrorMessages.maxLength(30),
               },
               pattern: {
-                value: /^[a-zA-Z0-9](?:[a-zA-Z0-9._]*[a-zA-Z0-9])?$/,
+                value: USERNAME_REGEX,
                 message: FormErrorMessages.invalidPattern,
               },
             })}