Add Media.Dropzone and Media.Preview as isolated elements

Introduce `Media.*` to modularize and customize file upload handling. Refactor media-related components to improve usability, add max item limits, overwrite support, and event callbacks.

app/src/ui/routes/test/tests/dropzone-element-test.tsx

@@ -0,0 +1,78 @@
+import { type DropzoneRenderProps, Media } from "ui/elements";
+import { Scrollable } from "ui/layouts/AppShell/AppShell";
+
+export default function DropzoneElementTest() {
+   return (
+      <Scrollable>
+         <div className="flex flex-col w-full h-full p-4 gap-4">
+            <div>
+               <b>Dropzone User Avatar 1 (fully customized)</b>
+               <Media.Dropzone
+                  entity={{ name: "users", id: 1, field: "avatar" }}
+                  maxItems={1}
+                  overwrite
+               >
+                  {(props) => <CustomUserAvatarDropzone {...props} />}
+               </Media.Dropzone>
+            </div>
+
+            <div>
+               <b>Dropzone User Avatar 1 (overwrite)</b>
+               <Media.Dropzone
+                  entity={{ name: "users", id: 1, field: "avatar" }}
+                  maxItems={1}
+                  overwrite
+               />
+            </div>
+
+            <div>
+               <b>Dropzone User Avatar 1</b>
+               <Media.Dropzone entity={{ name: "users", id: 1, field: "avatar" }} maxItems={1} />
+            </div>
+
+            <div>
+               <b>Dropzone Container blank w/ query</b>
+               <Media.Dropzone query={{ limit: 2 }} />
+            </div>
+
+            <div>
+               <b>Dropzone Container blank</b>
+               <Media.Dropzone />
+            </div>
+
+            <div>
+               <b>Dropzone Post 12</b>
+               <Media.Dropzone entity={{ name: "posts", id: 12, field: "images" }} />
+            </div>
+         </div>
+      </Scrollable>
+   );
+}
+
+function CustomUserAvatarDropzone({
+   wrapperRef,
+   inputProps,
+   state: { files, isOver, isOverAccepted, showPlaceholder },
+   actions: { openFileInput }
+}: DropzoneRenderProps) {
+   const file = files[0];
+
+   return (
+      <div
+         ref={wrapperRef}
+         className="size-32 rounded-full border border-gray-200 flex justify-center items-center leading-none overflow-hidden"
+      >
+         <div className="hidden">
+            <input {...inputProps} />
+         </div>
+         {showPlaceholder && <>{isOver && isOverAccepted ? "let it drop" : "drop here"}</>}
+         {file && (
+            <Media.Preview
+               file={file}
+               className="object-cover w-full h-full"
+               onClick={openFileInput}
+            />
+         )}
+      </div>
+   );
+}