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3.8 mb of sources duplicated from stage to stage and already superseded.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, 52 deletions

diff --git a/docs/history/10-zc/code/tests/umd.zc b/docs/history/10-zc/code/tests/umd.zc
deleted file mode 100644
index 7d1bffc..0000000
--- a/docs/history/10-zc/code/tests/umd.zc
+++ /dev/null
@@ -1,52 +0,0 @@
-// lists as [len, items...], items owned by the list
-fn mklist(n) -> u
-{
-	var l = new(n + 1);
-	l[0] = 0;
-	return l as u;
-}
-fn push(m l, d item) { l[l[0] + 1] = item as d; l[0] = l[0] + 1; return 0; }
-fn sum(m l) { var s = 0, i = 1; while (i <= l[0]) { s += l[i][0]; i++; } return s; }
-fn box(v) -> u { var b = new(1); b[0] = v; return b as u; }
-fn consume(d b) { return b[0]; }
-
-fn main()
-{
-	var base = live_objects();
-	{
-		var l = mklist(8);		// u from mklist arrives here as m
-		var i = 0;
-		while (i < 5) {
-			var b = box(i * 10);	// m in the loop body
-			b as d;			// give it down
-			push(l, b);
-			i++;
-		}
-		putn(sum(l)); putc(' ');
-		putn(live_objects() - base); putc(' ');	// list + 5 boxes
-	}
-	putn(live_objects() - base); putc(' ');	// freed at the block's end, children too
-
-	// u handed up one block by assignment, and as a block value
-	var outer;
-	{
-		var t = box(7);
-		t as u;
-		outer = t;
-	}
-	var v = { var w = box(8); w as u };
-	putn(outer[0] + v[0]); putc(' ');
-
-	// d given away to a callee
-	var g = box(99);
-	putn(consume(g as d)); putc(' ');
-
-	// containers: child takes its parent's tag
-	var p = new(2), c = new(1);
-	c[0] = 5;
-	p[0] = c;
-	p[1] = new(3);
-	putn(p[0][0]); putc(' ');
-	putn(live_objects() - base); putc(10);
-	return 0;
-}