A backup of .env is still a copy of the camera password

Editing .env leaves .env.bak-<timestamp> beside it, and only the
anchored /.env pattern was ignored - so the backup showed up as an
untracked file holding the RTSP password in plaintext, one `git add -A`
away from being committed. The pattern that protects the original has to
protect its copies.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Qiy5iKfz4L8S4vRaYPBdaU

.gitignore

@@ -52,3 +52,6 @@ node_modules/
 # in the tree `go build ./...` fails on a fresh checkout - on a machine that may
 # have no npm at all. They are ~200 KB and regenerating them is one command; a
 # repository that does not compile is the more expensive problem.
+
+# Backups of .env made when editing camera credentials.
+/.env.bak-*