feat(version): print the version like gh version

tea version and --version printed "Version: development<TAB>golang:
1.27.2". They now print "tea version 1.0.0 (2026-10-01)", the release
notes URL for tagged releases, and "built with go1.27.2" with the build
tags. Builds from go install take the module version from the build
info, and the date comes from the commit the binary was built from.

Signed-off-by: bircni <bircni@icloud.com>

internal/version/version_test.go

@@ -0,0 +1,30 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package version
+
+import (
+	"runtime/debug"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestFormatDescribesTheBuild(t *testing.T) {
+	stamped := &debug.BuildInfo{Settings: []debug.BuildSetting{{Key: "vcs.time", Value: "2026-10-01T09:30:00Z"}}}
+	for _, tc := range []struct {
+		name, version, tags string
+		info                *debug.BuildInfo
+		want                string
+	}{
+		{"release", "1.0.0", "", stamped, "tea version 1.0.0 (2026-10-01)\nhttps://gitea.com/gitea/tea/releases/tag/v1.0.0\nbuilt with go1.27.2"},
+		{"release candidate with tags", "1.1.0-rc1", "sqlite netgo", nil, "tea version 1.1.0-rc1\nhttps://gitea.com/gitea/tea/releases/tag/v1.1.0-rc1\nbuilt with go1.27.2 (tags: sqlite, netgo)"},
+		{"between releases", "0.16.0+12-gabcdef", "", stamped, "tea version 0.16.0+12-gabcdef (2026-10-01)\nbuilt with go1.27.2"},
+		{"go install", "development", "", &debug.BuildInfo{Main: debug.Module{Version: "v1.0.1"}}, "tea version 1.0.1\nhttps://gitea.com/gitea/tea/releases/tag/v1.0.1\nbuilt with go1.27.2"},
+		{"local build", "development", "", &debug.BuildInfo{Main: debug.Module{Version: "(devel)"}}, "tea version development\nbuilt with go1.27.2"},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			require.Equal(t, tc.want, format(tc.version, tc.tags, "go1.27.2", tc.info))
+		})
+	}
+}