chore: ignore editor swap files

A swap file of an ignored file is not itself ignored: .env.swp does not
match .env, and vim writes the buffer's contents into it. One was picked
up by an earlier commit.

Checked before writing this: the captured buffer predates the Authentik
credentials and holds only the development Postgres password, which is
labelled as such and reachable on 127.0.0.1 only. Nothing real leaked.
The repository has no remote yet, so the history can still be scrubbed
cheaply if you would rather it were.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012cSY9pVhZmJUKNN7wf1Myd

.gitignore

@@ -22,6 +22,12 @@ playwright-report/
 .env
 .env.local
 .env.*.local
+# An editor swap file of an ignored file is NOT itself ignored: .env.swp does
+# not match .env, and vim writes the buffer's contents into it.
+*.swp
+*.swo
+*~
+.*.sw[a-p]
 
 # database dumps & backups — but never the Prisma migrations, which are source
 backups/