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3.8 mb of sources duplicated from stage to stage and already superseded.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, 22 deletions

diff --git a/docs/history/17-o3-boundaries/code/tests/o3fat.zc b/docs/history/17-o3-boundaries/code/tests/o3fat.zc
deleted file mode 100644
index 313c87c..0000000
--- a/docs/history/17-o3-boundaries/code/tests/o3fat.zc
+++ /dev/null
@@ -1,22 +0,0 @@
-// o3 objects reaching normal code get their types: through a return (all the way down the list), an assignment, a store into a field
-struct node { int v; *node next; };
-struct box { [3]*node slots; int n; };
-unchecked o3 *node build(int n)
-{
-	*node head = 0;
-	for (int i = 0; i < n; i++) { *node k = new(node); k.v = i; k.next = head; head = k; }
-	return head;
-}
-unchecked fn main()
-{
-	*node l = build(5);
-	tprint(typeof_obj(l)); putc(' '); tprint(typeof_obj(l.next.next.next)); putc(' ');
-	putn(l.next.v); putc(' ');
-	*box b = 0;
-	o3 { b = new(box); b.slots[1] = new(node); b.n = 2; }
-	tprint(typeof_obj(b)); putc(' '); tprint(typeof_obj(b.slots[1])); putc(' ');
-	*int raw = 0;
-	o3 { raw = new(int, 6); }
-	tprint(typeof_obj(raw)); putc(10);
-	return 0;
-}