47e4e43310
Three compounding causes, found by tracing every place a `loading` flag is set
against every place it is cleared.
THE COST. `compose_screen` inflated EVERY entry in the pak and held every build
in memory at once, purely to index into the result -- then did it again on every
checkbox click, re-opening the ISO from scratch each time. But the catalog
already records each build's pak ENTRY INDEX, so the locator was there all
along: compose now reads exactly one entry. `RequestScreenCompose` carries
`entry` (the locator) beside `build` (the display ordinal).
`build_screen_catalog` had no budget at all, while the pak browser has capped
exactly this work since it was written. It now skips oversized entries and stops
at a ceiling.
That ceiling is 384 MB, not the pak browser's 64 MB, and the difference is the
point: GP_HANGAR_ARSENAL inflates past 160 MB and holds ~390 builds, so a 64 MB
cap would have quietly hidden most of them -- trading a hang for a wrong answer.
When the ceiling IS hit the pak is marked `truncated` and the UI says so.
THE LATCH. `poll_loader_channel` treated a disconnected channel exactly like an
empty one, so if a worker died every in-flight spinner stayed up for the life of
the process -- and the `if loading { return }` guard at the top of each handler
then refused every retry. Disconnect now clears the flags and reports it.
Verified: the workspace builds, the viewer reaches steady state, and one
composite still draws 11/11 elements of the tutorial pause menu.