fix(git): Prevent strpping hash-prefixed from commits

Sets `core.commentChar` to a semicolon (`;`). This prevents Git from
treating lines beginning with a `#` as comments and removing them from
the final commit message. This is useful when writing commit messages
with markdown.

home/modules/programs/git.nix

@@ -74,6 +74,9 @@
           credential = {
             helper = "store --file=${config.sops.secrets."git-credential".path}";
           };
+          core = {
+            commentChar = ";";
+          };
         };
         sops.secrets."git-credential" = {
           mode = "0640";