Fix bounty payout memo text

[cybercraftsolutionsllc]

Summary

• fixes bounty payout memos so keysend notifications include a clean bounty title instead of the current trailing s typo
• centralizes bounty payment memo formatting with an empty-title fallback
• refreshes payment test expectations and the generated database mock needed for handler tests to compile

Fixes #993.

Validation

• go test ./utils -run 'TestBuildBountyPaymentMemo|TestBuildV2KeysendBodyData' -count=1
• go test ./handlers -run '^$' -count=1
• git diff --check

go test ./handlers -run TestMakeBountyPayment -count=1 was attempted, but the local test database was not running at localhost:5532, so that integration-style test could not connect.