Stop the listings and their chapters stating fixed defects as fact

You were right that this was still everywhere. The two `.bas` files carried
their workarounds as present-tense statements about the interpreter -- "a name
first created inside a GOSUB costs a value slot that is never handed back",
"writing PAST the terminator of a short row draws nothing at all", "SSHAPE and
GSHAPE ignore the subscript on a string array", "a FOR inside a BEGIN block does
not survive the RETURN" -- and every one of those is now false. A comment that
lies is worse than no comment, and these were the first thing anybody opening
the files would read.

**The characters game takes the geometry fix.** `CW# = 16` becomes `CW# =
RGR(3)`, and the grid comes from `RWINDOW`, so the game fits whatever window and
font the host gives it. That was the one thing in the listing that would break on
a different font, and `RGR(3)` and `RWINDOW` were added to the interpreter
because of it -- leaving the constant in place while Chapter 17 teaches the
function was the inconsistency worth closing. `RGR(1)` still comes first so a
build with no graphics device refuses by naming the device that is missing.

Everything else in both listings keeps its shape and says why. Declaring every
name up front, guarding loops with `GOTO`, six scalars for six brick stamps: none
is forced any more and none costs anything, so they stay, with the comments
marking which rules stand and which are history. The sprites header's five traps
are marked FIXED where they are fixed.

The chapters follow: Chapter 17 Step 2 no longer says "the listing still has
`CW# = 16`", and Chapter 18's trap section is "five things that did not do what
they looked like" with the two that still stand named up front rather than left
to be counted.

Verified: Chapter 17 Step 2's block is once again verbatim from the listing, so
every quoted fragment in both chapters matches its source with no exceptions;
both games run 40 seconds on the SDL frontend with no error line; both suites
green in both configurations; `docs_examples` and `docs_screenshots --check`
pass.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

docs/17-tutorial-breakout.md

@@ -54,10 +54,10 @@ with it. That is Chapter 18.
 ## Step 2: Measure the screen once, at the top
 
 ```basic norun
-CW# = RGR(3)
-CH# = RGR(4)
 SCW# = RGR(1)
 SCH# = RGR(2)
+CW# = RGR(3)
+CH# = RGR(4)
 COLS# = RWINDOW(1)
 ROWS# = RWINDOW(0)
 ```
@@ -68,10 +68,14 @@ columns and rows — see [Chapter 6](06-graphics.md#rgr). Everything below is de
 these, including the ball's speed relative to the wall, so the game fits whatever window
 the host opened and whatever font it loaded.
 
-**The listing in `examples/` still has `CW# = 16` written out**, measured by hand against
-the bundled C64_Pro_Mono at 16 points, because when it was written a program had no way
-to ask — and it was the one thing in it that would break on a different font. That is
-what `RGR(3)` and `RWINDOW` are for; `TODO.md` §6 item 31 is the history.
+**The first version of this file had `CW# = 16` written out**, measured by hand against
+the bundled C64_Pro_Mono at 16 points, because there was no way to ask — and it was the
+one thing in the listing that would break on a different font. `RGR(3)` and `RWINDOW`
+were added to the interpreter because of it; `TODO.md` §6 item 31 is the history.
+
+The order matters only for the error you get without a graphics device: `RGR(1)` refuses
+first, naming the device that is missing, which is what should stop a game that cannot
+draw.
 
 Lay the rest of the geometry out in the same block — the wall in cells, the play area in
 pixels: