fix: add SSL cert validation bypass for Heroku Redis cache

Heroku Redis uses self-signed certificates. The rate limiter already
had this fix, but the cache Redis URL was missing it, causing
500 errors on all cached routes.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: ssk42

config.py

@@ -60,9 +60,24 @@ def get_database_uri():
 
     # Caching (Item 12)
     CACHE_TYPE = 'RedisCache' if os.getenv('REDIS_URL') else 'SimpleCache'
-    CACHE_REDIS_URL = os.getenv('REDIS_URL')
     CACHE_DEFAULT_TIMEOUT = 300
 
+    @staticmethod
+    def get_cache_redis_url():
+        """Get cache Redis URL with SSL fix for Heroku."""
+        uri = os.getenv('REDIS_URL')
+        if not uri:
+            return None
+        # Heroku Redis uses self-signed certificates, so we must ignore validation
+        if uri.startswith('rediss://') and 'ssl_cert_reqs' not in uri:
+            if '?' in uri:
+                uri += '&ssl_cert_reqs=none'
+            else:
+                uri += '?ssl_cert_reqs=none'
+        return uri
+
+    CACHE_REDIS_URL = get_cache_redis_url.__func__()
+
     # Rate Limiting
     @staticmethod
     def get_ratelimit_storage_uri():