Update golang version to `1.26` in `go.mod`

[rohanKanojia]

Description

⚠️ Blocked until go-toolset releases 1.26 version
The latest release of controller-runtime v0.24.0 requires Go 1.26 as a minimum version. To upgrade to the latest controller-runtime and benefit from its improvements and bug fixes, we need to first bump our Go version.

Acceptance Criteria

• Update go.mod to require Go 1.26
• Update Go toolchain version
• Update CI/CD workflows to use Go 1.26
• Update Dockerfiles to use Go toolset 1.26 base images when available
• Test build and unit tests with Go 1.26