fix: set vc-follow-symlinks explicitly to t

The line read `(setq-default vc-follow-symlinks)` with no value. That left the variable at nil, so the comment "don't ask to follow symlinks if target is version controlled" was a lie. Opening any version-controlled symlink still prompted.

I checked the Emacs docs first. The value `t` is the one that follows the link without asking, so that's what I set.

I added `tests/test-system-defaults-vc-follow-symlinks.el` as a regression test. It loads the module with the unrelated side effects stubbed and asserts `vc-follow-symlinks` ends up as `t`.

0 files changed, 0 insertions, 0 deletions