fix(gateway): guard chained .get() against None intermediate values

.get("key", {}) only applies the default when the key is ABSENT.
When the key exists with value None (null in JSON), .get() returns
None and the subsequent .get() raises AttributeError.

Fix: replace .get("key", {}).get(...) with (.get("key") or {}).get(...)
which handles both missing keys AND None values.

8 instances across 6 files:
- gateway/run.py: tool_call function name check
- acp_adapter/server.py: tool name/description extraction
- gateway/platforms/qqbot/onboard.py: API response task_id
- gateway/platforms/yuanbao.py: message content parsing (x2)
- gateway/platforms/slack.py: block text extraction (x2)
- tui_gateway/server.py: error message extraction

plugins/platforms/slack/adapter.py

@@ -6683,7 +6683,7 @@ class SlackAdapter(BasePlatformAdapter):
         original_text = ""
         for block in message.get("blocks", []):
             if block.get("type") == "section":
-                original_text = block.get("text", {}).get("text", "")
+                original_text = (block.get("text") or {}).get("text", "")
                 break
 
         # Slack re-escapes HTML entities in the interaction payload
@@ -6862,7 +6862,7 @@ class SlackAdapter(BasePlatformAdapter):
         original_text = ""
         for block in message.get("blocks", []):
             if block.get("type") == "section":
-                original_text = block.get("text", {}).get("text", "")
+                original_text = (block.get("text") or {}).get("text", "")
                 break
 
         # Slack re-escapes HTML entities in the interaction payload
@@ -6964,7 +6964,7 @@ class SlackAdapter(BasePlatformAdapter):
         original_text = ""
         for block in message.get("blocks", []):
             if block.get("type") == "section":
-                original_text = block.get("text", {}).get("text", "")
+                original_text = (block.get("text") or {}).get("text", "")
                 break
 
         from tools import clarify_gateway as _clarify_mod