mods/diff: pinned header with body-only scroll, the built-in's list and base chords, wheel routing, and the DiffDialog off fullscreen - #94184

…turned up since the start is session work, and each file but the diff's last keeps git's closing line

…le's hunks under an eight-row list, rows that scroll to their file, no focus or close mark of its own, /diff's transcript line) and the inline pane as its dialog

…he moved-in file and /diff's answers

…rsing, so hunks parsed for another backend stay as printed

… every other name drawn

…ction and dimColor, a pane's closeOnEscape and holdToasts, and ui.scroll's by and contentRows; the command fixtures name their presentation

…them three rows a tick (the pane answers ui.scroll itself), the list keys and ctrl+x b press Buttons that declare the built-in's actions, rows rest grey, toasts are held, and without the fullscreen layout /diff opens the built-in dialog's shape inline, focused, at any width

… its window, and off fullscreen /diff opens the dialog, lists five files a page and shows one alone

….scroll's pointer), and the dialog opens as tall as its content (ui.open's rows)

… the ring's walk selects, the five rows re-centring on it as the built-in's do (ui.focus)

… the files a hooks module may link

…-in's does, where the ring would wrap

# Conflicts:
#	mods/diff/hooks/register.ts
#	mods/diff/hooks/views/detail/code-blocks-of/code-blocks-of.ts
#	mods/diff/tests/fixtures/git-in.ts
#	mods/diff/tests/fixtures/in-repository.ts
#	mods/diff/tests/fixtures/index.ts
#	mods/telemetry/tests/fixtures/index.ts

…leaf's cap, draw only their lines in view, and stop at the tree's budget