Cleanup: Deduplicate tip strings in launcher tip_exit()

[cmkobel]

Summary

In the launcher script ./comparem2 (lines ~84–88), the tip_exit() function appends the same URL strings multiple times:

• Documentation URL appended 3 times
• GitHub issues URL appended 2 times

This appears to be intentional (to weight random selection), but it's unclear and fragile.

Proposed approach

If the repetition is for weighted random selection, make that explicit — e.g., use random.choices() with weights. If unintentional, deduplicate.

Files to touch

• comparem2 (lines ~80–105, tip_exit() function)