Refactor Go CI workflow for better structure and coverage #1

	name: Go CI / Test / Lint

	on:
	push:
	branches: [ "main" ]
	pull_request:
	branches: [ "main" ]

	jobs:
	ci:
	runs-on: ubuntu-latest

	strategy:
	matrix:
	go-version: [1.20, 1.21]

	steps:
	# Checkout code
	- name: Checkout repository
	uses: actions/checkout@v4

	# Go setup
	- name: Setup Go
	uses: actions/setup-go@v4
	with:
	go-version: ${{ matrix.go-version }}

	# Cache modules and build cache
	- name: Cache Go build & modules
	uses: actions/cache@v3
	with:
	path: \|
	~/.cache/go-build
	~/go/pkg/mod
	key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
	restore-keys: \|
	${{ runner.os }}-go-

	# Ensure dependencies
	- name: Go mod tidy
	run: go mod tidy

	# Lint
	- name: Run golangci-lint
	uses: golangci/golangci-lint-action@v4
	with:
	version: v1.59.0
	args: run --timeout 5m

	# Build
	- name: Build code
	run: go build -v ./...

	# Test + coverage
	- name: Run tests with coverage
	run: \|
	go test ./... -coverprofile=coverage.out -failfast -timeout=30s
	go tool cover -func=coverage.out

	# Upload coverage report (optional)
	- name: Upload coverage to Codecov
	if: github.event_name != 'pull_request'
	uses: codecov/codecov-action@v4
	with:
	files: coverage.out

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