chore: untrack the .wt-station-g3-prod worktree

A worktree checked out inside the repo, caught by a `git add -A` and recorded
as a gitlink. Same problem df070833 fixed for .build-wt-028a5dca, and the same
fix: untrack it and widen the ignore rule, which only covered .build-wt-*.

It is not harmless. The gitlink pointed at a different commit than the worktree
had checked out, so `git status` was permanently dirty — which is how it nearly
got re-committed here, and it makes CI checkouts warn about a submodule path
with no .gitmodules entry.

The worktree directory is gone; branch fix/station-g3-ota-manifest-base and its
commit are untouched. That branch still carries one commit not on prod —
5000391c, which adds OTA_MANIFEST_BASE to the station_g3 variant. It belongs on
prod, whose build.sh does not yet inject that flag, and must NOT come to dev,
where build.sh does and an .ini declaration cannot be overridden (SCons reorders
-U/-D) — it would pin dev and beta builds to the production manifest.

.gitignore

@@ -25,7 +25,10 @@ platformio.local.ini
 .cursor/*
 .claude/*
 .cursorrules
-# Throwaway build worktrees; committing one adds a stray gitlink that makes every
-# CI checkout warn "No url found for submodule path ... in .gitmodules".
+# Worktrees checked out inside the repo. Committing one adds a stray gitlink
+# that makes every CI checkout warn "No url found for submodule path ... in
+# .gitmodules", and leaves `git status` permanently dirty so the next `git add
+# -A` re-commits it. .wt-* covers the hand-made ones; .build-wt-* the CI ones.
 .build-wt-*/
+.wt-*/
 scripts/__pycache__/*