docs: archive the frozen stage code as one compressed tarball

docs/history kept six stages with a full copy of the project under code/,
3.8 mb of sources duplicated from stage to stage and already superseded. store
them as docs/history/code-snapshots.tar.gz, 0.66 mb, and extract one in place
to read it. every stage's notes.md stays browsable, and the index says where the
code went and how to get it back.

the top-level README points at the archive too. its other two links into
docs/history, 21-micro and 35-bench, were notes that were never kept and do not
resolve; the index now records that.

1 files changed, 0 insertions, 19 deletions

diff --git a/docs/history/17-o3-boundaries/code/tests/o3scopes.zc b/docs/history/17-o3-boundaries/code/tests/o3scopes.zc
deleted file mode 100644
index 9457c77..0000000
--- a/docs/history/17-o3-boundaries/code/tests/o3scopes.zc
+++ /dev/null
@@ -1,19 +0,0 @@
-// registers reused by scopes that never overlap, and a fixed array read through its cached items and length
-o3 int scopes(fixed []int f)
-{
-	int total = 0;
-	for (int a = 0; a < 3; a++) { int x = a * 2; total += x; }
-	for (int b = 0; b < 3; b++) { int y = b * 3; total += y; }
-	for (int c = 0; c < 3; c++) { int z = c * 5; total += z; }
-	for (int e = 0; e < len(f); e++) { int w = f[e]; total += w; }
-	for (int g = 0; g < 4; g++) { int h = g + 1, q = h * h, r = q - 1; total += r; }
-	return total;
-}
-fn main()
-{
-	fixed []int f = new(fixed []int, 4);
-	for (int i = 0; i < 4; i++) f[i] = 10 * i;
-	putn(scopes(f)); putc(10);
-	free(d*f);
-	return 0;
-}