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.

internal/browser/session.go

@@ -9,7 +9,6 @@ import (
 	"path/filepath"
 	"sort"
 	"strings"
-	"sync"
 	"time"
 )
 
@@ -20,8 +19,6 @@ import (
 // is the same as Playwright's storage state so sessions are interchangeable.
 type SessionStore struct {
 	root string
-
-	mu sync.Mutex
 }
 
 // SessionInfo describes a persisted session, returned to the MCP client by