fix: sanitize tool call IDs in agent loop for Mistral strict9 format (#23595) (#23698)

* fix: sanitize tool call IDs in agent loop for Mistral strict9 format (#23595)

Mistral requires tool call IDs to be exactly 9 alphanumeric characters
([a-zA-Z0-9]{9}). The existing sanitizeToolCallIdsForCloudCodeAssist
mechanism only ran on historical messages at attempt start via
sanitizeSessionHistory, but the pi-agent-core agent loop's internal
tool call → tool result cycles bypassed that path entirely.

Changes:
- Wrap streamFn (like dropThinkingBlocks) so every outbound request
  sees sanitized tool call IDs when the transcript policy requires it
- Replace call_${Date.now()} in pendingToolCalls with a 9-char hex ID
  generated from crypto.randomBytes
- Add Mistral tool call ID error pattern to ERROR_PATTERNS.format so
  the error is correctly classified for retry/rotation

* Changelog: document Mistral strict9 tool-call ID fix

---------

Co-authored-by: echoVic <AkiraVic@outlook.com>
Co-authored-by: Vincent Koc <vincentkoc@ieee.org>

src/agents/pi-embedded-helpers/errors.ts

@@ -614,6 +614,7 @@ const ERROR_PATTERNS = {
     "tool_use_id",
     "messages.1.content.1.tool_use.id",
     "invalid request format",
+    /tool call id was.*must be/i,
   ],
 } as const;