fix: security hardening across platform

- Disable open /api/auth/register endpoint (gateway)
- Require gateway session auth on Immich and Karakeep hooks proxies
- Replace SHA-256 with bcrypt in fitness service (auth + seed)
- Remove hardcoded Telegram user IDs from fitness seed
- Add Secure flag to session cookie
- Add domain allowlist and content-type validation to image proxy
- Strengthen .gitignore (env variants, runtime data, test artifacts)

gateway/integrations/image_proxy.py

@@ -1,5 +1,5 @@
 """
-Platform Gateway — Image proxy (bypass hotlink protection).
+Platform Gateway — Image proxy with domain allowlist.
 """
 
 import urllib.request
@@ -7,24 +7,65 @@ import urllib.parse
 
 from config import _ssl_ctx
 
+ALLOWED_IMAGE_DOMAINS = {
+    "i.redd.it",
+    "preview.redd.it",
+    "external-preview.redd.it",
+    "i.imgur.com",
+    "imgur.com",
+    "images-na.ssl-images-amazon.com",
+    "m.media-amazon.com",
+    "cdn.discordapp.com",
+    "media.discordapp.net",
+    "pbs.twimg.com",
+    "abs.twimg.com",
+    "upload.wikimedia.org",
+    "images.unsplash.com",
+}
+
 
 def handle_image_proxy(handler):
-    """Proxy external images to bypass hotlink protection (e.g. Reddit)."""
+    """Proxy external images to bypass hotlink protection."""
     qs = urllib.parse.urlparse(handler.path).query
     params = urllib.parse.parse_qs(qs)
     url = params.get("url", [None])[0]
     if not url:
         handler._send_json({"error": "Missing url parameter"}, 400)
         return
+
+    # Validate URL scheme and domain allowlist
+    try:
+        parsed = urllib.parse.urlparse(url)
+        if parsed.scheme not in ("http", "https"):
+            handler._send_json({"error": "Invalid URL scheme"}, 400)
+            return
+        hostname = parsed.hostname or ""
+        if hostname not in ALLOWED_IMAGE_DOMAINS:
+            allowed = any(
+                hostname == d or hostname.endswith(f".{d}")
+                for d in ALLOWED_IMAGE_DOMAINS
+            )
+            if not allowed:
+                print(f"[ImageProxy] Blocked request for domain: {hostname}")
+                handler._send_json({"error": "Domain not allowed"}, 403)
+                return
+    except Exception:
+        handler._send_json({"error": "Invalid URL"}, 400)
+        return
+
     try:
         req = urllib.request.Request(url, headers={
             "User-Agent": "Mozilla/5.0 (compatible; PlatformProxy/1.0)",
             "Accept": "image/*,*/*",
-            "Referer": urllib.parse.urlparse(url).scheme + "://" + urllib.parse.urlparse(url).netloc + "/",
+            "Referer": parsed.scheme + "://" + parsed.netloc + "/",
         })
         resp = urllib.request.urlopen(req, timeout=10, context=_ssl_ctx)
         body = resp.read()
         ct = resp.headers.get("Content-Type", "image/jpeg")
+        # Only serve actual image content types
+        if not ct.startswith("image/"):
+            handler._send_json({"error": "Response is not an image"}, 400)
+            return
         handler.send_response(200)
         handler.send_header("Content-Type", ct)
         handler.send_header("Content-Length", len(body))