Say "boot image" where that is what is meant

"Binary" was doing three jobs. It meant an SPBT file that the machine starts
from; it meant whatever the assembler happened to produce, which is now
either that or a loadable program; and it meant a compiled host tool. A word
that means three things means none of them, and the first of the three has a
name already - this project has been calling them boot images for a while
and the manuals had not caught up.

  Where it means an SPBT file       -> boot image
  Where it means either output      -> output
  Where it means a host executable  -> left alone
  Where it means base two           -> left alone

The user facing messages move with it:

  Error: No boot image specified.
  Usage: ./SplitBit [OPTIONS] <boot image>
  Error: This is not a SplitBit boot image.
  Error: This boot image is in format version 2, and this emulator reads 1.
  Successfully wrote SplitBit boot image to "hello.bin".

The assembler's own help was the interesting case. Its -o writes either
format, so "the binary" there was never right - it is "the output" now, and
the message that names the format is the one that says which it wrote.

No recorded output contained the word, so nothing needed re-blessing.
Checked before starting rather than after.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW

Programs/CosmOS/Assembler/scratch.asm

@@ -17,7 +17,7 @@
 ;
 ;   0x8000  3072   the label index, 768 entries of four
 ;   0x8C00  8192   the label names, packed end to end
-;   0xAC00 13312   the binary being built
+;   0xAC00 13312   the output file being built
 ;   0xE000  1792   the vector names, 64 entries of twenty eight
 ;   0xE700  1758   the reader's stack, six levels of 293
 ;   0xEE00   368   which files have been included, sixteen names of 23