build(cli): make vhs recordings _more_ reproducible

- use `gomod2nix` to prouduce nix flake builds of git-cc
- use `libfaketime` and its binary `faketime` to limit the range of possible git hashes for the demo recording

Unfortunately, `vim` still takes a random amount of time to save the config file, so the recordings aren't yet wholly reproducible.

charmbracelet/vhs#257 should help!

.envrc

@@ -1,4 +1,4 @@
 #!/usr/bin/env sh
 unset GOPATH GOROOT
 use flake
-export PATH="${PWD}/dist:$PATH" # always use most recent build for real git-cc
+export PATH="${PWD}/result/bin:$PATH" # always use most recent build for real git-cc

Makefile

@@ -13,7 +13,7 @@ test-rpm-install: test-release-process
 #^ requires that GITHUB_TOKEN be set, and the token have the 'repo' scope
 
 ./assets/demo.mp4: ./assets/demo.tape
-	cat ./assets/demo.tape | vhs
+	faketime '2000-01-01 00:00:00' vhs ./assets/demo.tape
 
 changelog:
 	pnpx standard-version
@@ -24,4 +24,4 @@ clean:
 	rm -rf dist
 
 # so to cut a release, run `make changelog`, inspect the changes, and then run
-# `git push --tags --follow-tags`
+# `git push --tags --follow-tags`

assets/demo.tape

@@ -51,25 +51,30 @@ Set Height 800
 
 Hide
 
-Type@1ms "export PATH=$(pwd)/dist:$PATH old_dir=$(pwd) new_dir=/tmp/git-repo"
+
+Type@0ms "export old_dir=$(pwd) new_dir=/tmp/git-repo"
 Enter
 
-Type@1ms "rm -rf $new_dir && mkdir -p $new_dir && cd $new_dir"
+Require git
+Require git-cc
+Require vim
+
+Type@0ms "set -euo pipefail"
 Enter
 
-Type@1ms "cp $old_dir/commit_convention.yaml $new_dir && git init && git checkout -b main"
+Type@0ms "rm -rf $new_dir && mkdir -p $new_dir && cd $new_dir"
 Enter
 
-Type@1ms "touch ./foo && git add foo"
+Type@0ms "cp $old_dir/commit_convention.yaml $new_dir && git init && git checkout -b main"
 Enter
 
-Type@1ms "export LD_PRELOAD=$(nix-build '<nixpkgs>' --no-build-output -A libfaketime)/lib/libfaketime.so.1 FAKETIME='2000-01-01 00:00:00'"
+Type@0ms "touch ./foo && git add foo"
 Enter
 
-Type@1ms "clear"
+Type@0ms "clear"
 Enter
 
-Type@1ms "export EDITOR=vi"
+Type@0ms "export EDITOR=vi"
 Enter
 Show
 
@@ -93,13 +98,13 @@ Enter
 # enter a new scope
 Sleep 200ms
 Escape
-Type "12G"
+Type "12G" # go to line 12
 Enter
-Type "$"
-Type "i"
+Type "$" # go to the end of the line
+Type "i" # enter insert mode
 Right
 Enter
-Backspace 2
+# Backspace 2
 Type "- scope: description of scope"
 Escape
 Type ":wq"