Make non-robot test setup explicit

Make non-robot test setup explicit

Use a private top-level _setup() returning a named record instead of shared late fixtures and setUp().

Call _setup() explicitly at the beginning of each unit/controller test and destructure its named record. Keep fixture builders at top level, outside group bodies. Robot tests use the robot lifecycle instead. This rule does not ban late generally: Flutter lifecycle fields and other established lazy initialization patterns are separate concerns. The detector reports newly written late or setUp lines when both patterns coexist in the test.

Detection scope

This detector recognizes specific textual patterns; it is not a complete semantic analyzer. Explicit user instructions and applicable repository conventions take precedence.