[CPCAP-4585] Update third parties and dependencies

[pranavcracker]

Summary

This PR upgrades the project toolchain to Go 1.25 to address known vulnerabilities, migrates golangci-lint to v2, and updates Docker base images and dependencies to versions compatible with the new Go release.
Changes are limited to CI, tooling, Docker images, and dependencies; no application logic was modified.

Key Changes

• Security & Toolchain

  • Upgraded Go from 1.24 → 1.25 (CI workflows and Docker images) to address vulnerabilities
  • Updated Go-based Docker images to Go 1.25.5
  • Updated Python base image to python:3.13.11-alpine

• Linting

  • Upgraded golangci-lint-action to v7 (golangci-lint v2)
  • Added .golangci.yml (config version 2) required by golangci-lint v2
  • Disabled selected style-only Staticcheck rules and errcheck to avoid large refactors in legacy and generated code
  • Core correctness checks (typecheck, govet, etc.) remain enabled

• Dependencies

  • Updated Go module dependencies to versions compatible with Go 1.25
  • Pinned sigs.k8s.io/controller-runtime to v0.21.0 to avoid breaking API changes