Rename RL_INDEX_API_BLOCKED_IPS key to use colon separator

'rl:index:api_blocked_ips' -> 'rl:index:api:blocked_ips' for
consistent colon-delimited key naming convention.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

sapl/middleware/ratelimit.py

@@ -78,7 +78,7 @@ RL_INDEX_BLOCKED_USERS = 'rl:index:blocked_users'
 # API-specific rate limit keys — scope limited to /api/, never written by non-/api/ paths.
 RL_API_IP_REQUESTS = 'rl:api:ns:{ns}:ip:{ip}:reqs'
 RL_API_IP_BLOCKED = 'rl:api:ns:{ns}:ip:{ip}:blocked'
-RL_INDEX_API_BLOCKED_IPS = 'rl:index:api_blocked_ips'
+RL_INDEX_API_BLOCKED_IPS = 'rl:index:api:blocked_ips'
 
 # ---------------------------------------------------------------------------
 # API quota keys — per-consumer, per-day/week, tenant-scoped.