ci: use the shared pull request, release and autoupdate workflows (#1)

* ci(release): add goreleaser and semver configuration

The release builds only cmd/readitall for Linux, macOS and Windows on amd64 and arm64. The checksum file is signed with cosign. The semver config uses regex matching. A major release needs an explicit trailer line.

* ci: add shared pull request, release and autoupdate workflows

The workflows call the shared workflows in lukaszraczylo/shared-actions. The release runs on push to main when Go files change.

* docs: describe release binary installation

The README now tells you to download a binary from the GitHub release page.

* fix(browser): remove the unused mutex field of SessionStore

Staticcheck reports U1000 for the field. No method locks it. The
pull request checks fail until the field is removed.

.github/workflows/autoupdate.yaml

@@ -0,0 +1,20 @@
+name: Autoupdate go.mod and go.sum
+
+on:
+  workflow_dispatch:
+  schedule:
+    - cron: "0 3 * * *"
+
+permissions:
+  contents: write
+  actions: write
+  pull-requests: write
+  security-events: write
+
+jobs:
+  autoupdate:
+    uses: lukaszraczylo/shared-actions/.github/workflows/go-autoupdate.yaml@main
+    with:
+      go-version: ">=1.26"
+      release-workflow: "release.yaml"
+    secrets: inherit

.github/workflows/pr.yaml

@@ -0,0 +1,22 @@
+name: Pull Request
+
+on:
+  pull_request:
+    branches:
+      - main
+  push:
+    branches:
+      - "**"
+      - "!main"
+
+permissions:
+  contents: write
+  actions: write
+  pull-requests: write
+  security-events: write
+
+jobs:
+  pr-checks:
+    uses: lukaszraczylo/shared-actions/.github/workflows/go-pr.yaml@main
+    with:
+      go-version: ">=1.26"

.github/workflows/release.yaml

@@ -0,0 +1,23 @@
+name: Release
+
+on:
+  push:
+    branches:
+      - main
+    paths:
+      - "**.go"
+      - "go.mod"
+      - "go.sum"
+  workflow_dispatch:
+
+permissions:
+  contents: write
+  packages: write
+  id-token: write
+
+jobs:
+  release:
+    uses: lukaszraczylo/shared-actions/.github/workflows/go-release.yaml@main
+    with:
+      go-version: ">=1.26"
+    secrets: inherit