refactor: no expiring command, and a file's last commit is its hash and age (#20)

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

README.md

@@ -23,8 +23,7 @@ A terminal UI for finding, reading and sharing secrets. Inspired by the fantasti
 - **Favourites**: star the secrets you use most and get back to them in one
   key.
 - **Expiry warnings**: secrets, keys and certificates that expire soon are
-  marked, listed together in the status pane, and `lazysecrets expiring`
-  checks every vault from a pipeline.
+  marked, and listed together in the status pane.
 - **Your way**: rebind any key, pick a theme, and add custom commands to run
   on a secret.
 - **Try it first**: `lazysecrets --demo` runs on built-in sample data.