cinny: 303 /share-target → /share for the PWA share target (#155)

The service worker normally answers the share-sheet POST itself; this
keeps a POST that reaches nginx before the worker controls the page from
returning 405.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

cinny/nginx.conf

@@ -77,6 +77,13 @@ server {
         proxy_connect_timeout 5;
     }
 
+    # [Gitea #155] PWA share target. The service worker normally answers this
+    # POST itself; if it isn't controlling the page yet, land on /share
+    # (the shared files are lost, but nothing 405s).
+    location = /share-target {
+        return 303 /share;
+    }
+
     location / {
         rewrite ^/config\.json$          /config.json break;
         rewrite ^/manifest\.json$        /manifest.json break;