chore: upgrade CI infrastructure to support Go 1.25

[leonorfmartins]

Description

Upgrades Kepler's CI infrastructure to support Go 1.25, based on #2496 (stalled, reopened here).

• Dockerfile: builder base image golang:1.24 → golang:1.25
• .github/workflows/pr-checks.yaml: golangci-lint action v2.1.6 → v2.12.2
• .pre-commit-config.yaml: golangci-lint hook v2.1.6 → v2.12.2

Ran in Linux containers matching CI (ubuntu-latest). make image command + tests pass locally.

Part of #2491

[bitflicker64]

Change is correct and I would take it. The image jobs (build-images, build-and-deploy, compose-deploy) all pass here, which is the direct evidence that the golang:1.25 bump is safe.

One suggestion runs through the two golangci-lint lines: v2.13.2 rather than v2.12.2 would also clear the Go 1.26 step, for both the action and the pre-commit hook, and those two need it for different reasons. Details on each line.

Thanks for crediting #2496 up front in the description. The hunk text is identical across all three files; Dockerfile and .pre-commit-config.yaml even have the same pre- and post-image blob hashes in both PRs, and pr-checks.yaml differs only because main moved underneath it. Whichever of the two lands, #2492 and #2496 want closing in the same pass so the next dependabot bump does not arrive to three competing fixes.

[bitflicker64]

checked the open question from my review myself. ran a full golangci-lint run ./... on main (a6eacd80) in a golang:1.25 linux container, with both versions built from source the way the pre-commit hook builds them. v2.1.6 and v2.12.2 report the same 3 errcheck warnings in internal/server/probe_test.go (422, 430, 462), all pre-existing, and nothing new. so the bump is clean.

the v2.13.2 suggestion and the multi-arch-builds.md line are both optional. fine to merge without them, and my 3 threads can be resolved whenever it goes in. per vibhu in slack, this should land after the next release.

[Copilot]

Copilot review overview

🟢 Approval recommended

The infrastructure versions are consistent and valid; only a minor stale documentation reference remains.

Review effort: Balanced
Findings: 1

Open (1)

• Update multi-architecture guide to reference golang:1.25 · New

What changed in this PR

Upgrades CI and container build tooling for Go 1.25 compatibility.

Changes:

• Uses Go 1.25 for container builds.
• Aligns local and CI golangci-lint at v2.12.2.

File	Description
Dockerfile	Updates the builder image to Go 1.25.
.pre-commit-config.yaml	Updates the local golangci-lint hook.
.github/​workflows/​pr-checks.yaml	Updates the CI golangci-lint version.

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[bitflicker64]

Blocking: no. Score: 10/10. Summary: The builder image moves to golang:1.25, and golangci-lint moves to v2.12.2 in both the workflow and the pre-commit hook. The multi-arch doc now links the Dockerfile and says golang:<go-version> instead of a fixed version, which addresses the open Copilot thread on Dockerfile:2. Evidence: build-images, build-and-deploy, compose-deploy and pre-commit pass at 4248100. The branch is up to date with main. The Dockerfile has the only golang image tag in the tree. v2.12.2 has a linux-amd64 release binary for the lint action to download. The Go paths filter skipped lint, fmt, vet and test-and-codecov, so the workflow pin first runs on the next PR that touches Go files. A full golangci-lint run ./... at v2.12.2 on a6eacd8 (main at the time) reported the same 3 errcheck warnings as v2.1.6, and all 3 were there before this PR.