Fix chat URL routing and agent.php fact_type column error

- sendMessage() was fetching /api.php?action=chat which bypasses the
  /api/* rewrite rule; api.php parsed endpoint as "api.php" → 404.
  Fixed to /api/chat so the rewrite routes it correctly to chat.php.

- agent.php HA entity map INSERT used non-existent fact_type column,
  causing PDOException on every agent heartbeat. Fixed to use the
  correct (category, fact_key, fact_value) columns.

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

api/endpoints/agent.php

@@ -184,7 +184,7 @@ switch ($agentAction) {
             ];
         }
         JarvisDB::query(
-            'INSERT INTO kb_facts (fact_key, fact_value, fact_type) VALUES ("ha/entity_map", ?, "json")
+            'INSERT INTO kb_facts (category, fact_key, fact_value) VALUES ("ha_entities", "ha/entity_map", ?)
              ON DUPLICATE KEY UPDATE fact_value=VALUES(fact_value), updated_at=NOW()',
             [json_encode($entityMap)]
         );