feat: LinkedIn video upload working + static file serving

- Add /public static route to serve files from /vaults/public
- Fix LinkedIn API version: 202501 → 202603 (active version)
- OpenAPI schema already included POST /api/linkedin/video
- Successfully posted Remotion video to LinkedIn

src/manifest.ts

@@ -342,6 +342,30 @@ export function getOpenApiSpec(serverUrl: string) {
           responses: { '200': { description: 'Post created' } },
         },
       },
+      '/api/linkedin/video': {
+        post: {
+          operationId: 'linkedin_upload_video',
+          summary: 'Upload video and create LinkedIn post',
+          requestBody: {
+            required: true,
+            content: {
+              'application/json': {
+                schema: {
+                  type: 'object',
+                  required: ['video_url', 'text'],
+                  properties: {
+                    video_url: { type: 'string', description: 'Publicly accessible URL of the MP4 video' },
+                    text: { type: 'string' },
+                    visibility: { type: 'string', enum: ['PUBLIC', 'CONNECTIONS'] },
+                    account: { type: 'string' },
+                  },
+                },
+              },
+            },
+          },
+          responses: { '200': { description: 'Video uploaded and posted' } },
+        },
+      },
 
       // ── Telegram ────────────────────────────────────────────────
       '/api/telegram/message': {