chore(deps): bump google.golang.org/adk from 0.3.0 to 0.4.0

Bumps [google.golang.org/adk](https://github.com/google/adk-go) from 0.3.0 to 0.4.0.
- [Release notes](https://github.com/google/adk-go/releases)
- [Commits](google/adk-go@v0.3.0...v0.4.0)

---
updated-dependencies:
- dependency-name: google.golang.org/adk
  dependency-version: 0.4.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

go.mod

@@ -12,7 +12,7 @@ require (
 	github.com/agentplexus/vaultguard v0.2.0
 	github.com/cloudwego/eino v0.7.28
 	github.com/go-playground/validator/v10 v10.30.1
-	google.golang.org/adk v0.3.0
+	google.golang.org/adk v0.4.0
 	google.golang.org/genai v1.43.0
 	gopkg.in/yaml.v3 v3.0.1
 )

go.sum

@@ -278,8 +278,8 @@ golang.org/x/text v0.33.0/go.mod h1:LuMebE6+rBincTi9+xWTY8TztLzKHc/9C1uBCG27+q8=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 gonum.org/v1/gonum v0.16.0 h1:5+ul4Swaf3ESvrOnidPp4GZbzf0mxVQpDCYUQE7OJfk=
 gonum.org/v1/gonum v0.16.0/go.mod h1:fef3am4MQ93R2HHpKnLk4/Tbh/s0+wqD5nfa6Pnwy4E=
-google.golang.org/adk v0.3.0 h1:gitgAKnET1F1+fFZc7VSAEo7cjK+D39mnRyqIRTzyzY=
-google.golang.org/adk v0.3.0/go.mod h1:iE1Kgc8JtYHiNxfdLa9dxcV4DqTn0D8q4eqhBi012Ak=
+google.golang.org/adk v0.4.0 h1:CJ31nyxkqRfEgKuttR4h3o6QFok94Ty4UpbefUn21h8=
+google.golang.org/adk v0.4.0/go.mod h1:jVeb7Ir53+3XKTncdY7k3pVdPneKcm5+60sXpxHQnao=
 google.golang.org/genai v1.43.0 h1:8vhqhzJNZu1U94e2m+KvDq/TUUjSmDrs1aKkvTa8SoM=
 google.golang.org/genai v1.43.0/go.mod h1:A3kkl0nyBjyFlNjgxIwKq70julKbIxpSxqKO5gw/gmk=
 google.golang.org/genproto/googleapis/api v0.0.0-20260114163908-3f89685c29c3 h1:X9z6obt+cWRX8XjDVOn+SZWhWe5kZHm46TThU9j+jss=