build(ci): migrate .golangci.yml to v2 schema (closes #62)

[dipto0321]

Summary

.golangci.yml targets the v2 schema (version: "2") — fixing the silent-parse-failure mode that made make lint and make ci completely unusable for any contributor with a current Homebrew (which ships v2.x by default today). CI bumps golangci/lint-action@v6 → @v8 and pins version: v2.12.2 to match what Homebrew installs locally. The Makefile lint target now checks for the binary and prints the exact go install ...@v2.12.2 command matching the CI pin when missing.

Same lint set + exclusion rules + presets that v1 ran with still apply — confirmed by make ci showing 0 issues locally on a Homebrew v2.12.2 install.

Linked issues

Closes #62

Type of change

• feat — new feature (MINOR bump)
• fix — bug fix (PATCH bump)
• refactor — no behavior change
• perf — performance improvement
• docs — documentation only
• test — tests only
• chore — maintenance / dependency bump
• ci — CI/CD only
• build — build system only
• Breaking change (MAJOR bump) — explain below

Checklist

• Title follows Conventional Commits (feat(scope): subject)
• I ran make ci locally and it passes (tidy/fmt/vet/lint/test all green, 0 lint issues)
• I added or updated tests for the change (not applicable — CI schema change)
• I updated relevant docs (README, docs/, inline comments)
• No new linter warnings
• If breaking: I documented the migration path in the PR body and updated CHANGELOG.md

Screenshots / output

Pre-fix reproduction (Homebrew's stock v2.12.2):

$ make lint
golangci-lint run ./...
Error: can't load config: can't unmarshal config by viper (flags, file): 1 error(s) decoding:

* 'output.formats' expected a map, got 'slice'
The command is terminated due to an error: can't load config: can't unmarshal config by viper (flags, file): 1 error(s) decoding:

* 'output.formats' expected a map, got 'slice'
make: *** [lint] Error 3

make ci had the same blocker (lint is in its dependency chain), so the documented local-dev workflow was effectively broken for any contributor with Homebrew's current default — they could only run vet/test, never lint.

Post-fix (same Homebrew v2.12.2):

$ make ci
go mod tidy
gofmt -s -w .
goimports not installed, skipping (...)
go vet ./...
golangci-lint run ./...
0 issues.
go test -race -coverprofile=coverage.out -covermode=atomic ./...
ok  	github.com/dipto0321/nodeup/internal/cli	coverage: 29.2%
ok  	github.com/dipto0321/nodeup/internal/config	coverage: 81.0%
ok  	github.com/dipto0321/nodeup/internal/detector	coverage: 76.8%
ok  	github.com/dipto0321/nodeup/internal/node	coverage: 71.5%
ok  	github.com/dipto0321/nodeup/internal/packages	coverage: 37.4%
ok  	github.com/dipto0321/nodeup/internal/platform	coverage: 55.6%

Missing-binary case (handy because contributors won't always have golangci-lint installed):

$ make lint
golangci-lint not installed.
Install the version pinned in .github/workflows/ci.yml with:
  go install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@v2.12.2
(or update both this Makefile and ci.yml together when bumping).
make: *** [lint] Error 1

Files touched

• .golangci.yml — migrated to the v2 schema with golangci-lint migrate. Top-of-file comments (which migrate warns it strips) were re-added by hand to preserve the rationale for the lint set + exclusion paths. Schema-level diff:
  • version: "2" field added.
  • output.formats is now a map (text:), not a list — fixing the v1-vs-v2 parse failure.
  • linters.disable-all: true → linters.default: none.
  • linters-settings: → linters.settings:.
  • gofmt / goimports moved from linters.enable: into a new top-level formatters: block (v2's grammar for fmt-vs-lint).
  • goimports.local-prefixes is now a list, not a single string.
  • New linters.exclusions: block preserves v1's per-rule exclusions (test files, windows-only symbols, upgrade.go cross-file refs) and adds v2's presets: [comments, common-false-positives, legacy, std-error-handling] for the broader exclusion grammar.
  • gosimple is removed from enable: (folded into staticcheck in v2). Everything else (bodyclose, contextcheck, errcheck, gocritic, govet, ineffassign, misspell, staticcheck, unused) stays.
• .github/workflows/ci.yml —
  • golangci/golangci-lint-action@v6 → @v8.
  • version: v1.64.8 → v2.12.2 (matches Homebrew's current default so local matches CI byte-for-byte).
  • Comment block explains the v2 pin and references build(lint): .golangci.yml v1 schema incompatible with golangci-lint v2 (brew installs v2, make lint fails to even parse config) #62.
• Makefile — lint: target now checks for the binary first; if missing, prints the exact go install github.com/golangci/golangci-lint/v2/cmd/golangci-lint@v2.12.2 command (matching the CI pin) so a missing-install surfaces a fix-it hint, not an exec failure.
• CHANGELOG.md — ### Fixed entry under [Unreleased] documenting the migration with the build(lint): .golangci.yml v1 schema incompatible with golangci-lint v2 (brew installs v2, make lint fails to even parse config) #62 reference.

[cocogitto-bot]

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