feat(v4.0.0): assemble definitions written as text

Test support, beside the slot packer: reads definitions in the notation
DECOMPOSITION.md uses -- words, opcodes, literals, constants, labels,
branches, FOR NEXT and FOR UNEXT, in-line macros, comments -- and lays
them down through the slot packer, so they no longer have to be retyped
opcode by opcode in C.

Tested by assembling SWAP, UM/MOD, C@ and C! both ways on two nodes and
comparing memory word for word, by running what is assembled, and on
every error it reports, each with its line number.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

v4/README.md

@@ -16,7 +16,9 @@ and every ISA, hosted and bare metal, must still reach its `ok` prompt.
 What exists so far is the single node: registers, circular stacks, memory, all
 32 opcodes, per-opcode and per-call-target heat, and three console
 registers (`CONSOLE-TX`, which captures output, and `CONSOLE-RX` and `CONSOLE-STATUS`, which hand out
-input a test feeds) standing in for the console node until the mesh exists. `make -C v4 test` builds
+input a test feeds) standing in for the console node until the mesh exists. The tests load definitions
+onto a node either opcode by opcode (`v4/include/v4/asm.h`) or as text in the notation `DECOMPOSITION.md`
+uses (`v4/include/v4/text.h`). `make -C v4 test` builds
 and runs the tests at both cell widths; `make -C v4 sanitize` repeats them
 under ASan and UBSan. There is no compiler capsule, no POST and no K
 measurement yet.