chore(security): bump go directive to 1.25.12

govulncheck fails on the 1.25.10 standard library: GO-2026-5037
(crypto/x509 hostname parsing), GO-2026-5039 (net/textproto error
escaping), and GO-2026-5856 (crypto/tls), the last fixed only in
1.25.12. All are reached through pre-existing call paths (client.Call,
auth.Login) and are unrelated to the auth change on this branch — main
last ran green on 2026-05-25, before these were published, so it would
fail there too today.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012MvqxTC64Z9EEDewCUbNNo

Author: DTTerastar

go.mod

@@ -1,6 +1,6 @@
 module github.com/quantcli/withings-export-cli
 
-go 1.25.10
+go 1.25.12
 
 require (
 	github.com/quantcli/common/compat v0.0.0-20260511001927-62c4c6634ff5