feat: feedback with photo support + web dashboard feedback button

iOS:
- Photo picker in feedback sheet (screenshot/photo attachment)
- Image sent as base64, uploaded to Gitea issue as attachment

Web:
- Feedback button in sidebar rail
- Modal with text area + send
- Auto-labels same as iOS

Gateway:
- Multipart image upload to Gitea issue assets API

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

gateway/feedback.py

@@ -98,10 +98,39 @@ def handle_feedback(handler, body, user):
         )
         resp = urllib.request.urlopen(req, timeout=10)
         result = json.loads(resp.read())
+        issue_number = result.get("number")
+
+        # Upload image attachment if provided
+        image_b64 = data.get("image")
+        if image_b64 and issue_number:
+            import base64
+            try:
+                img_bytes = base64.b64decode(image_b64)
+                boundary = "----FeedbackBoundary123"
+                body_parts = []
+                body_parts.append(f"--{boundary}\r\n".encode())
+                body_parts.append(b'Content-Disposition: form-data; name="attachment"; filename="screenshot.png"\r\n')
+                body_parts.append(b"Content-Type: image/png\r\n\r\n")
+                body_parts.append(img_bytes)
+                body_parts.append(f"\r\n--{boundary}--\r\n".encode())
+                multipart_body = b"".join(body_parts)
+
+                img_req = urllib.request.Request(
+                    f"{GITEA_URL}/api/v1/repos/{REPO}/issues/{issue_number}/assets",
+                    data=multipart_body,
+                    headers={
+                        "Authorization": f"token {GITEA_TOKEN}",
+                        "Content-Type": f"multipart/form-data; boundary={boundary}",
+                    },
+                    method="POST",
+                )
+                urllib.request.urlopen(img_req, timeout=15)
+            except Exception as img_err:
+                pass  # Image upload failed but issue was created
 
         handler._send_json({
             "ok": True,
-            "issue_number": result.get("number"),
+            "issue_number": issue_number,
             "url": result.get("html_url"),
         })
     except Exception as e: