fix(main): only trust build version when major matches module path

debug.ReadBuildInfo() can report a version whose major version does
not match the module path's major version suffix (e.g. a v2 tag on a
module without a /v2 path), which is unreliable per Go's module
versioning rules. Extract the decision into resolveVersion() and only
accept the build version when its major matches the module path's
implied major version, otherwise fall back to the dev version.

Fixes #231.

Co-Authored-By: Codet <codet@commitgo.dev> (GPT-5-Codex)

main_test.go

@@ -0,0 +1,61 @@
+package main
+
+import (
+	"runtime/debug"
+	"testing"
+)
+
+func TestResolveVersion(t *testing.T) {
+	cases := []struct {
+		name string
+		dev  string
+		info *debug.BuildInfo
+		want string
+	}{
+		{
+			name: "nil build info falls back to dev version",
+			dev:  "dev",
+			info: nil,
+			want: "dev",
+		},
+		{
+			name: "devel version falls back to dev version",
+			dev:  "dev",
+			info: &debug.BuildInfo{Main: debug.Module{Path: "gitea.com/gitea/gitea-mcp", Version: "(devel)"}},
+			want: "dev",
+		},
+		{
+			name: "empty version falls back to dev version",
+			dev:  "dev",
+			info: &debug.BuildInfo{Main: debug.Module{Path: "gitea.com/gitea/gitea-mcp", Version: ""}},
+			want: "dev",
+		},
+		{
+			name: "v1 version accepted for module path without major suffix",
+			dev:  "dev",
+			info: &debug.BuildInfo{Main: debug.Module{Path: "gitea.com/gitea/gitea-mcp", Version: "v1.2.3"}},
+			want: "v1.2.3",
+		},
+		{
+			name: "v2 version rejected when module path has no /v2 suffix",
+			dev:  "dev",
+			info: &debug.BuildInfo{Main: debug.Module{Path: "gitea.com/gitea/gitea-mcp", Version: "v2.0.0"}},
+			want: "dev",
+		},
+		{
+			name: "v2 version accepted when module path has /v2 suffix",
+			dev:  "dev",
+			info: &debug.BuildInfo{Main: debug.Module{Path: "gitea.com/gitea/gitea-mcp/v2", Version: "v2.0.0"}},
+			want: "v2.0.0",
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			got := resolveVersion(tc.dev, tc.info)
+			if got != tc.want {
+				t.Errorf("resolveVersion(%q, %+v) = %q, want %q", tc.dev, tc.info, got, tc.want)
+			}
+		})
+	}
+}