feat: Gitea Actions CI/CD, Docker registry images, drive drag-and-drop

- Add .gitea/workflows/docker-build.yml: builds backend and frontend
  Docker images on every push, pushes to Gitea Container Registry
  (git.necloud.us/nate/cloudlink/{backend,frontend}:latest + SHA tag)
- Add desktop build job: Linux AppImage and Windows NSIS installer via
  Wine cross-compilation, uploaded as workflow artifacts
- Add release job: creates a Gitea release with installers attached when
  a v* tag is pushed
- Add deploy job: SSH pull + restart on pushes to master
- docker-compose.yml: add image: fields alongside build: so the server
  can pull pre-built images with docker compose pull
- DrivePage: add drag-and-drop upload with full-screen drop overlay;
  refactor upload logic into a shared uploadFile callback

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

frontend/src/pages/DrivePage.tsx

@@ -1,4 +1,4 @@
-import { useRef, useState, useEffect } from 'react';
+import { useRef, useState, useEffect, useCallback } from 'react';
 import { useQuery, useQueryClient } from '@tanstack/react-query';
 import { Upload, File, Trash2, Download, Lock } from 'lucide-react';
 import { formatDistanceToNow } from 'date-fns';
@@ -34,6 +34,7 @@ export default function DrivePage() {
   const qc = useQueryClient();
   const inputRef = useRef<HTMLInputElement>(null);
   const [uploading, setUploading] = useState(false);
+  const [dragOver, setDragOver] = useState(false);
   const [decryptedNames, setDecryptedNames] = useState<Record<string, string>>({});
 
   const { data: files = [] } = useQuery<DriveFile[]>({
@@ -60,11 +61,9 @@ export default function DrivePage() {
     })();
   }, [files, masterKey]);
 
-  async function handleUpload(e: React.ChangeEvent<HTMLInputElement>) {
-    const file = e.target.files?.[0];
-    if (!file || !masterKey) return;
+  const uploadFile = useCallback(async (file: File) => {
+    if (!masterKey) return;
     setUploading(true);
-
     try {
       const fileKey = await generateFileKey();
       const encryptedBlob = await encryptFile(file, fileKey);
@@ -83,6 +82,18 @@ export default function DrivePage() {
       setUploading(false);
       if (inputRef.current) inputRef.current.value = '';
     }
+  }, [masterKey, qc]);
+
+  function handleUpload(e: React.ChangeEvent<HTMLInputElement>) {
+    const file = e.target.files?.[0];
+    if (file) uploadFile(file);
+  }
+
+  function handleDrop(e: React.DragEvent) {
+    e.preventDefault();
+    setDragOver(false);
+    const file = e.dataTransfer.files[0];
+    if (file) uploadFile(file);
   }
 
   async function handleDownload(f: DriveFile) {
@@ -125,11 +136,25 @@ export default function DrivePage() {
         <input ref={inputRef} type="file" className="hidden" onChange={handleUpload} />
       </header>
 
-      <div className="flex-1 overflow-y-auto p-6">
+      <div
+        className="flex-1 overflow-y-auto p-6"
+        onDragOver={(e) => { e.preventDefault(); setDragOver(true); }}
+        onDragLeave={() => setDragOver(false)}
+        onDrop={handleDrop}
+      >
+        {dragOver && (
+          <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/60 pointer-events-none">
+            <div className="flex flex-col items-center gap-3 bg-surface-1 border-2 border-dashed border-accent rounded-2xl px-16 py-12">
+              <Upload className="w-12 h-12 text-accent" />
+              <p className="text-lg font-semibold">Drop to encrypt &amp; upload</p>
+            </div>
+          </div>
+        )}
+
         {files.length === 0 ? (
           <div className="flex flex-col items-center justify-center h-48 text-slate-500 gap-3">
             <File className="w-10 h-10" />
-            <p>No files yet — upload your first encrypted file</p>
+            <p>No files yet — drag &amp; drop or click Upload</p>
           </div>
         ) : (
           <div className="grid grid-cols-1 gap-2">