fix(server): Claude answers stream as they are written#24410

Merge remote-tracking branch 'origin/main' into fix/issue-17270

fix(server): empty streamed Claude text keeps the result fallback

test(server): reproduces #17270 empty fallback

test(server): cover Claude text stream settlement and suppression paths

Merge main into fix/issue-17270

fix(server): Claude answers stream as they are written

test(server): Claude assistant text streams before the final snapshot