doc: Add a tapes/ folder (#873)

We can put VHS tapes for demos here.
These will not be rendered at doc build time
as that'll change literally every build (git hashes).

We can set up infrastructure to render them deterministically
(similarly to test scripts) in the future if we really want to,
but even then because the VHS tapes run in real time,
that will significantly slow down docs (and will likely be flaky in CI).

So the tapes folder is just for future reference
to recreate any demos if we want to.

[skip changelog]: no user facing changes

Author: abhinav

.gitattributes

@@ -8,6 +8,7 @@
 *.txt text eol=lf
 
 *.png filter=lfs diff=lfs merge=lfs -text
+*.gif filter=lfs diff=lfs merge=lfs -text
 
 # pgregory.net/rapid should be considered generated code to reduce noise.
 **/testdata/rapid/**/*.fail linguist-generated

doc/tapes/20250924-branch-split-reuse-name.gif

@@ -0,0 +1,24 @@
+# Demo of 'branch split' supporting moving the branch name.
+
+Output "20250924-branch-split-reuse-name.gif"
+Hide
+
+# Setup
+Type "cd $(mktemp -d) && git init && git commit --allow-empty -m 'Initial commit'" Enter
+Type "gs repo init && git config spice.experiment.commitFixup true" Enter
+Type "mkdir pangolin && touch pangolin/climb && git add pangolin && git comit -m 'Invent pangolins'" Enter
+Type "mkdir penguin && touch penguin/{swim,fish} && git add penguin && gs branch create penguin -m 'Invent penguins'" Enter
+Type "touch pangolin/roll && git add pangolin/roll && git commit -m 'Refactor pangolin'" Enter
+Type "clear" Enter
+Show
+
+Sleep 0.5s
+Type "git status" Enter Sleep 1s
+Type "gs ll" Enter Sleep 1s
+
+Type "gs branch split" Enter Sleep 2s
+Enter Sleep 1s Enter Sleep 1s
+Type "penguin" Enter Sleep 1s
+Type "refac-pangolin" Enter Sleep 1s
+
+Type "gs ll" Enter Sleep 3s

doc/tapes/20250924-branch-split-reuse-name.tape

@@ -0,0 +1,32 @@
+# Demo of 'commit fixup' for the 0.18 release notes.
+# Not used for the documentation.
+
+Output "20250924-commit-fixup.gif"
+Hide
+
+# Setup
+Type "cd $(mktemp -d) && git init && git commit --allow-empty -m 'Initial commit'" Enter
+Type "gs repo init && git config spice.experiment.commitFixup true" Enter
+Type "mkdir penguin && touch penguin/{flight,fish} && git add penguin && gs branch create penguin -m 'Invent penguins'" Enter
+Type "mkdir iguana && touch iguana/{climb,run} && git add iguana && gs branch create iguana -m 'Invent iguanas'" Enter
+Type "touch penguin/swim" Enter
+Type "clear" Enter
+Show
+
+Sleep 0.5s
+
+Type "ls penguin" Enter Sleep 1s
+Type "git status" Enter Sleep 1s
+Type "gs ll" Enter Sleep 1s
+
+Type "# penguins can swim but they can't fly" Enter Sleep 1s
+Type "git add penguin/swim" Enter Sleep 0.5s
+Type "git rm penguin/flight" Enter Sleep 0.5s
+
+Type "gs commit fixup" Enter
+Sleep 1s
+Down Sleep 0.5s Enter Sleep 1s
+
+Type "gs ll" Enter Sleep 1s
+Type "git status" Enter Sleep 1s
+Type "ls penguin" Enter Sleep 5s

doc/tapes/20250924-commit-fixup.gif

@@ -0,0 +1,4 @@
+[vhs](https://github.com/charmbracelet/vhs) tapes for demos and documentation.
+
+These are _not_ rendered at documentation build time
+as they can be slow to render and flaky in reproducibility.