[dayfine]

Depends on #485

Base lab/slice4-prechecks; the diff is one empty commit. This PR holds a design note only: FRLG AutoStory is not on this base. It lives on the FRLG stack (program added in #352 frlg/stage1-program, current code at the stack tip #458 frlg/stage20-league), which does not contain upstream/frlg-free-party-slots. Per the brief I did not merge the FRLG stack in.

Where it must stack. A branch off the FRLG stack tip (frlg/stage20-league once its agent is done, or frlg/stage19-victory-road now) with lab/slice4-prechecks merged in. A trial git merge-tree of #485 into both is conflict-free. That merge also brings upstream/frlg-free-party-slots (PokemonAutomation#1881) into the FRLG stack, which needs the user's OK.

What I'd change there. In PokemonFRLG_AutoStory.cpp, program() today calls check_setup() and require_preflight() (Pokemon::StoryPreflight: video alive, controller ready, not HOME). I'd replace both with a PrecheckList built by a side-effect-free autostory_prechecks(...) and run by run_prechecks() before verify, the SID Helper stop and any reset:

• game_open (ALWAYS_RUNS, first): StoryPreflight's video/controller/not-HOME read, as a Precheck.
• black_border (ALWAYS_RUNS): the existing FRLG black border check from Prechecks: a program's start checks as a named list, FRLG RNG first #485.
• known_screen (ALWAYS_RUNS): title screen for 01.01 with NEW_GAME_FROM_TITLE, otherwise the overworld or the start menu; refuses a post-run summary or a battle.
• start_checkpoint (ALWAYS_RUNS, no console read): the start is chosen by checkpoint id, not by index, and refuses a dev-only row while Developer Mode is off; the start/end order and 01.01 rules from check_setup() move here.
• language (SKIPPABLE): LANGUAGE matches the cartridge, read from the title screen or start menu text where detectable; PASSED with "not detectable here" otherwise.
  The StoryRangeOptions dropdown would need an id accessor (start_id()) so a hidden row cannot shift the index. Native tests (in the style of PokemonFRLG_Prechecks_Tests) would check the list's names and order and that HOME frames, a mismatched language and a hidden checkpoint id each fail with nothing pressed. Programs without a list report unsupported.

Not tested: nothing to build.