Fix chat titles empty when conversation has thinking blocks (Anthropic)

When re-generating the title at the 3rd user message, the full
conversation history was passed as past-messages. For thinking models
(e.g. nubank-anthropic/opus-4.6), this history includes "reason" role
messages. normalize-messages converts them to {:type "thinking" ...}
content blocks, but title generation disables thinking (reason? false),
so the request carries thinking blocks without the :thinking parameter.
The Anthropic API responds with {:text ""}, which is truthy in Clojure,
so sanitize-title returns "" and overwrites any previously good title.

Fix: filter "reason" role messages out of title-past-messages before
the sync prompt call.

🤖 Generated with [eca](https://eca.dev)

Co-Authored-By: eca-agent <git@eca.dev>

Author: ericdallo

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Unreleased
 
 - Auto allow ask_user tool by default.
+- Fix chat titles becoming empty when conversation history contains thinking blocks (Anthropic).
 
 ## 0.127.0
 

src/eca/features/chat.clj

@@ -575,7 +575,8 @@
         (assert-compatible-apis-between-models! db chat-id provider model config)
         (when generate-title?
           (let [title-past-messages (when retitle?
-                                     (get-in db [:chats chat-id :messages] []))]
+                                     (->> (get-in db [:chats chat-id :messages] [])
+                                          (filterv #(not= "reason" (:role %)))))]
             (future* config
               (when-let [{:keys [output-text]} (llm-api/sync-prompt!
                                                 {:provider provider