Add version resolver (tag → strip-v / fall back to short SHA)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

internal/version/version.go

@@ -0,0 +1,20 @@
+package version
+
+import "regexp"
+
+var semverTag = regexp.MustCompile(`^refs/tags/v(\d+\.\d+\.\d+)$`)
+
+// Resolve returns the version string to use in artifact names.
+// Precedence: override > matching semver tag > short SHA.
+func Resolve(override, ref, sha string) string {
+	if override != "" {
+		return override
+	}
+	if m := semverTag.FindStringSubmatch(ref); m != nil {
+		return m[1]
+	}
+	if len(sha) > 7 {
+		return sha[:7]
+	}
+	return sha
+}

internal/version/version_test.go

@@ -0,0 +1,32 @@
+package version_test
+
+import (
+	"testing"
+
+	"github.com/leonmika/wails-release/internal/version"
+)
+
+func TestResolve(t *testing.T) {
+	cases := []struct {
+		name     string
+		override string
+		ref      string
+		sha      string
+		want     string
+	}{
+		{"override wins", "9.9.9", "refs/tags/v1.2.3", "abcdefg1234", "9.9.9"},
+		{"clean tag strips v", "", "refs/tags/v1.2.3", "abcdefg1234", "1.2.3"},
+		{"prerelease tag falls back to sha", "", "refs/tags/v1.2.3-rc1", "abcdefg1234", "abcdefg"},
+		{"non-tag ref falls back to sha", "", "refs/heads/main", "abcdefg1234", "abcdefg"},
+		{"empty ref falls back to sha", "", "", "abcdefg1234", "abcdefg"},
+		{"short sha shorter than 7 returned verbatim", "", "", "abc", "abc"},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			got := version.Resolve(c.override, c.ref, c.sha)
+			if got != c.want {
+				t.Fatalf("got %q, want %q", got, c.want)
+			}
+		})
+	}
+}