Commit message that explains why

Write a Conventional Commits message for this diff. Subject line max 72 chars, imperative mood; body explains why, not what; add a BREAKING CHANGE footer only if the public API changed.

{diff}

Example run: diff = the like endpoint switching .upsert(row) to .upsert(row, { onConflict: 'prompt_id,user_id', ignoreDuplicates: true })

fix(likes): ignore duplicate likes instead of failing

A plain upsert becomes INSERT ... ON CONFLICT DO UPDATE. prompt_likes has
no UPDATE policy, so liking an already-liked post (for example from a
second tab) was rejected by RLS. ignoreDuplicates turns it into
ON CONFLICT DO NOTHING, which only needs the existing INSERT policy.