tutor: half the length, and the parts people actually ask about

1297 lines to 498. The tutor had grown to the point where the things a
newcomer needs first were buried in the middle of a helix reference, and
two subsystems it never mentioned at all.

REORDERED by what is most different from editors people arrive from, and
each part now earns its place:

  1 THE MOUSE     acme's three buttons and the chords, trimmed
  2 PANES         NEW. Moving between them, in one place
  3 THE TTY       Ctrl-b, Shift-Esc, and what plain Esc does
  4 DETACHED      NEW. The core outliving the terminal showing it
  5 THE KEYS      the helix half, cut hard, practice blocks kept
  6 THE REST      PDFs, images, the language backend, scripting

PANES was scattered across 3.12, part 2 and the summary; it is one
section now, because "how do I get out of this pane" is the question
that actually gets asked. Ctrl-w hjkl, Esc, Shift-Esc, Ctrl-o/Ctrl-i,
Alt-n, Alt-c, and the three panes that have their own claim on Escape.

THE TTY gains the rule the old text got wrong. It said Esc "goes to the
program" in raw tty, full stop. It has not for a while: at a shell
PROMPT plain Esc hops away like Shift-Esc, and only a program that has
TAKEN the tty (vim, a pager) keeps it. That is `takesCommandLine` in
pardes.zig, and it is the difference between the toggle feeling
obvious and feeling arbitrary.

DETACHED did not exist in the tutor at all. `--detach`, `--attach`, the
Attach/Detach words and their chords, why the pane shells belong to the
session and never stop, why N frontends share ONE screen at the smallest
common grid, and that `--fs`/`--fs9` work in a daemon now.

THE KEYS lost the most: thirteen subsections became six, roughly thirty
practice blocks became six. What went is the enumeration a reference
does better; what stayed is the handful of blocks that teach the one
idea helix users do not arrive with -- motions SELECT, so `wd` is what
`dw` was -- plus the count rule, which is the other thing that surprises.

Part 6 documents `pty/`, `--fs9` and the `9p` word, none of which the
tutor knew about.

The first seven lines are byte-identical on purpose: test/snapshots/
tutor.golden pins them, and it regenerated unchanged.

ALSO REGENERATED: test/snapshots/builtins.golden, which had been stale
since the `9p` word was added a few changes ago -- one more builtin
shifts every row of the `SPC ?` listing below it. Nothing was wrong with
the code; the golden had simply not been updated with the feature. All
95 snapshot scripts pass.

0 files changed, 0 insertions, 0 deletions