#15998: fix: hide metadata block when only conversation_label is present

- Avoids cluttering TUI and simple direct chat sessions - Only shows conversation info block when there's useful metadata beyond just conversation_label - Fixes issue where TUI shows 'Conversation info (untrusted metadata): { conversation_label: openclaw-tui }' on every message <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> Prevents cluttering TUI and direct chat sessions by only displaying the conversation info block when there's meaningful metadata beyond just `conversation_label`. - Adds new check `hasUsefulConversationMeta` to filter out cases where only `conversation_label` is present - Fixes issue where TUI shows 'Conversation info (untrusted metadata): { conversation_label: openclaw-tui }' on every message - Logic is correct but includes a redundant condition (the first `Object.values().some()` check is unnecessary) <h3>Confidence Score: 4/5</h3> - This PR is safe to merge with minimal risk - it's a focused fix that improves UX without breaking functionality - Score reflects that the change is well-scoped, logically correct, and addresses a specific UX issue. Minor deduction for the redundant condition that could be simplified, but this doesn't affect correctness - No files require special attention _{Last reviewed commit: 1b51363} <!-- greptile_other_comments_section --> _{(2/5) Greptile learns from your feedback when you react with thumbs up/down!} <!-- /greptile_comment -->