go.mod, go.sum: bump dependencies for v0.29.0

Refresh direct deps (tailscale v1.98.1, modernc.org/sqlite v1.50.1 +
libc v1.72.3 lockstep, otel cluster v1.43.0, x/* family, pgx v5.9.2,
go-jose v3.0.5, grpc v1.81.1, grpc-gateway v2.29.0) and bulk-update
remaining direct deps. tailscale held at v1.98.1 since v1.98.2 demands
go 1.26.3 which nixpkgs unstable does not yet ship.