Bump google.golang.org/grpc to v1.79.3 (#2329)

Addresses CVE-2026-33186 (SNYK-GOLANG-GOOGLEGOLANGORGGRPC-15691172):
Incorrect Authorization in gRPC-Go.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: twmb

backend/go.mod

@@ -71,7 +71,7 @@ require (
 	google.golang.org/genproto v0.0.0-20260217215200-42d3e9bedb6d
 	google.golang.org/genproto/googleapis/api v0.0.0-20260217215200-42d3e9bedb6d
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20260217215200-42d3e9bedb6d
-	google.golang.org/grpc v1.79.1
+	google.golang.org/grpc v1.79.3
 	google.golang.org/protobuf v1.36.11
 )
 

backend/go.sum

@@ -623,8 +623,8 @@ google.golang.org/genproto/googleapis/api v0.0.0-20260217215200-42d3e9bedb6d h1:
 google.golang.org/genproto/googleapis/api v0.0.0-20260217215200-42d3e9bedb6d/go.mod h1:48U2I+QQUYhsFrg2SY6r+nJzeOtjey7j//WBESw+qyQ=
 google.golang.org/genproto/googleapis/rpc v0.0.0-20260217215200-42d3e9bedb6d h1:t/LOSXPJ9R0B6fnZNyALBRfZBH0Uy0gT+uR+SJ6syqQ=
 google.golang.org/genproto/googleapis/rpc v0.0.0-20260217215200-42d3e9bedb6d/go.mod h1:4Hqkh8ycfw05ld/3BWL7rJOSfebL2Q+DVDeRgYgxUU8=
-google.golang.org/grpc v1.79.1 h1:zGhSi45ODB9/p3VAawt9a+O/MULLl9dpizzNNpq7flY=
-google.golang.org/grpc v1.79.1/go.mod h1:KmT0Kjez+0dde/v2j9vzwoAScgEPx/Bw1CYChhHLrHQ=
+google.golang.org/grpc v1.79.3 h1:sybAEdRIEtvcD68Gx7dmnwjZKlyfuc61Dyo9pGXXkKE=
+google.golang.org/grpc v1.79.3/go.mod h1:KmT0Kjez+0dde/v2j9vzwoAScgEPx/Bw1CYChhHLrHQ=
 google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
 google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=