#13247: Fix: Filter out Gemini 3 Pro thinking text

Fix: Filter out Gemini 3 Pro thinking text <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> Unable to complete PR review yet because the environment blocked access to required tooling (Jira search permission prompt appeared unexpectedly). Please grant the requested permission or disable the Jira integration so I can proceed to read the diff and review `src/agents/pi-embedded-utils.ts` against the base branch. <h3>Confidence Score: 0/5</h3> - Review not completed due to blocked tooling permissions. - I could not access the necessary PR context/diff because a permission prompt blocked the Jira search tool call before I could begin code review. - src/agents/pi-embedded-utils.ts <!-- greptile_other_comments_section --> _{(3/5) Reply to the agent's comments like "Can you suggest a fix for this @greptileai?" or ask follow-up questions!} <!-- /greptile_comment -->