fix: inline video upload in artefacts — drop modal, add drag-and-drop + progress bar

- Replace the two-step video modal with inline drag-and-drop zone + click-to-browse
- Add Google Drive URL input directly in the versions tab
- Add upload progress bar with percentage via XHR
- Support onUploadProgress in api.upload()

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

client/src/utils/api.js

@@ -79,11 +79,32 @@ export const api = {
     credentials: 'include',
   }).then(r => handleResponse(r, `DELETE ${path}`)),
   
-  upload: (path, formData) => fetch(`${API}${path}`, {
-    method: 'POST',
-    credentials: 'include',
-    body: formData,
-  }).then(r => handleResponse(r, `UPLOAD ${path}`)),
+  upload: (path, formData, opts = {}) => {
+    if (opts.onUploadProgress) {
+      return new Promise((resolve, reject) => {
+        const xhr = new XMLHttpRequest()
+        xhr.open('POST', `${API}${path}`)
+        xhr.withCredentials = true
+        xhr.upload.onprogress = (e) => {
+          if (e.lengthComputable) opts.onUploadProgress({ loaded: e.loaded, total: e.total })
+        }
+        xhr.onload = () => {
+          if (xhr.status >= 200 && xhr.status < 300) {
+            try { resolve(normalize(JSON.parse(xhr.responseText))) } catch { resolve(xhr.responseText) }
+          } else {
+            reject(new Error(`Upload failed: ${xhr.status}`))
+          }
+        }
+        xhr.onerror = () => reject(new Error('Upload failed'))
+        xhr.send(formData)
+      })
+    }
+    return fetch(`${API}${path}`, {
+      method: 'POST',
+      credentials: 'include',
+      body: formData,
+    }).then(r => handleResponse(r, `UPLOAD ${path}`))
+  },
 };
 
 // Brand color palette — dynamically assigned from a rotating palette