Refactor CSS styles across multiple components for improved consistency and maintainability

- Removed redundant styles and consolidated common styles in styles.scss
- Updated layout and spacing variables for better responsiveness
- Simplified component-specific styles in apartment, lease, tenant, and dashboard components
- Enhanced readability and organization of CSS by utilizing CSS layers
- Ensured consistent use of design tokens for colors, spacing, and borders

frontend/src/app/components/apartment-form/apartment-form.css

@@ -1,83 +1,9 @@
 :host {
   display: block;
 }
-.page-heading {
-  margin-bottom: 30px;
-}
-.page-heading h1 {
-  margin-bottom: 8px;
-  font-size: clamp(2rem, 7vw, 3.2rem);
-  font-weight: 750;
-  letter-spacing: -0.055em;
-  line-height: 1.02;
-}
-.page-heading > div > p:last-child {
-  margin-bottom: 0;
-  color: var(--text-muted);
-  line-height: 1.6;
-}
-.back-action.mat-mdc-button {
-  --mdc-text-button-label-text-color: var(--text-muted);
-  margin: 0 0 20px -16px;
-}
-.apartment-form {
-  padding: 20px;
-  border: 1px solid var(--border);
-  border-radius: 22px;
-  background: var(--surface);
-  box-shadow: 0 1px 0 rgba(255, 255, 255, 0.04);
-}
-.form-grid {
-  display: grid;
-  grid-template-columns: minmax(0, 1fr);
-  gap: 2px;
-}
-.form-grid mat-form-field {
-  width: 100%;
-}
-.alert-error {
-  margin-bottom: 18px;
-  padding: 13px 15px;
-  border: 1px solid color-mix(in srgb, var(--danger) 28%, transparent);
-  border-radius: 12px;
-  background: var(--danger-soft);
-  color: var(--danger);
-  font-size: 0.87rem;
-}
 .form-actions {
-  display: flex;
-  flex-direction: column-reverse;
-  gap: 8px;
   margin-top: 6px;
 }
-.form-actions button {
-  width: 100%;
-}
-@media (min-width: 700px) {
-  .page-heading {
-    display: flex;
-    align-items: flex-end;
-    justify-content: space-between;
-    gap: 28px;
-  }
-  .apartment-form {
-    padding: 30px;
-  }
-  .form-grid {
-    grid-template-columns: repeat(2, minmax(0, 1fr));
-    column-gap: 18px;
-  }
-  .full-field {
-    grid-column: span 2;
-  }
-  .form-actions {
-    flex-direction: row;
-    justify-content: flex-end;
-  }
-  .form-actions button {
-    width: auto;
-  }
-}
 @media (min-width: 1180px) {
   .form-page {
     max-width: 900px;