v1.2.0

What's changed

• Upgrade go.k6.io/k6/v2 to v2.0.0 (stable; was v2.0.0-rc1) — unblocks SQL driver extensions migrating to k6 v2
• Security: bump golang.org/x/net to v0.55.0, golang.org/x/sys to v0.44.0
• Go toolchain directive to 1.25.11
• Tooling/deps maintenance

No public API changes.