fix: minimize and zeroize owned password buffers

src/main.rs

@@ -103,6 +103,8 @@ Navigation:
   Left/Right changes TLS when focused. Enter connects and updates that saved entry
   only on success; failures keep the previous settings and connection. Esc discards edits.
   Passwords are masked, never saved, and clear on success or cancellation.
+  Owned input buffers are zeroized on clear/drop; profile saving does not copy passwords.
+  This does not erase driver copies, prior input allocations, or protect a compromised host.
   Ctrl-U clears a field; pasting is supported.
   Enter the database user explicitly; the operating-system username is not used.
   Configurations persist in $XDG_CONFIG_HOME/dbdash/connections.sqlite3, falling