Feat: FileManager (#98) (#703)

* feat: add file manager module

- Complete file manager implementation with UI/UX
- Add drive management functionality
- Add file upload/download with progress tracking
- Add stamp integration and handling
- Add bulk operations and context menus

Co-authored-by: Roland Seres <roland.seres90@gmail.com>
Co-authored-by: nidishk <nidishkrishnan45@gmail.com>

src/modules/filemanager/components/CustomDropdown/CustomDropdown.scss

@@ -0,0 +1,86 @@
+.fm-custom-dropdown {
+  position: relative;
+  width: 100%;
+  font-size: 14px;
+  user-select: none;
+
+  .fm-custom-dropdown-selected {
+    padding: 8px 12px;
+    border: 1px solid rgb(209, 213, 219);
+    border-radius: 0px;
+    background: #fff;
+    color: rgb(55, 65, 81);
+    cursor: pointer;
+    position: relative;
+    transition: border-color 0.2s;
+    outline: none;
+    display: flex;
+    align-items: center;
+    min-height: 40px;
+
+    .placeholder {
+      color: #aaa;
+    }
+
+    & .arrow {
+      position: absolute;
+      right: 12px;
+      top: 50%;
+      transform: translateY(-50%) rotate(0deg);
+      width: 16px;
+      height: 16px;
+      pointer-events: none;
+      display: inline-block;
+      transition: transform 0.2s;
+    }
+
+    &.open .arrow {
+      transform: translateY(-50%) rotate(180deg);
+    }
+
+    &:focus,
+    &.open {
+      border-color: rgb(237, 129, 49);
+    }
+  }
+
+  .fm-custom-dropdown-list {
+    position: absolute;
+    left: 0;
+    right: 0;
+    top: calc(100% + 4px);
+    background: #fff;
+    border: 1px solid rgb(209, 213, 219);
+    border-radius: 0px;
+    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
+    z-index: 20;
+    margin: 0;
+    padding: 4px 0;
+    list-style: none;
+    max-height: 220px;
+    overflow-y: auto;
+    animation: fadeIn 0.15s;
+
+    li {
+      padding: 10px 16px;
+      cursor: pointer;
+      color: rgb(55, 65, 81);
+      transition: background 0.15s;
+      &:hover,
+      &.selected {
+        background: #f5f5f5;
+      }
+    }
+  }
+}
+
+@keyframes fadeIn {
+  from {
+    opacity: 0;
+    transform: translateY(-8px);
+  }
+  to {
+    opacity: 1;
+    transform: translateY(0);
+  }
+}