feat: ship Rust login manager and GitLab release pipeline

Replace the legacy Go implementation as the production path, quarantine the reference tree, add deterministic release packaging and version metadata, and run verification through GitLab CI.

legacy/go/session/scan.go

@@ -0,0 +1,149 @@
+// session — environment scanning from xsessions, wayland-sessions,
+// and custom script directories. Includes desktop entry parser.
+//
+// Mirrors vendor/src/post_login/mod.rs:get_envs and parse_desktop_entry.
+package session
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+type DesktopEntry struct {
+	Name         string
+	Exec         string
+	DesktopNames string
+	Hidden       bool
+	NoDisplay    bool
+}
+
+func parseDesktopEntry(path string) (*DesktopEntry, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return nil, fmt.Errorf("open %s: %w", path, err)
+	}
+	defer f.Close()
+
+	e := &DesktopEntry{}
+	inSection := false
+	sc := bufio.NewScanner(f)
+	for sc.Scan() {
+		line := strings.TrimSpace(sc.Text())
+		if line == "" || line[0] == '#' {
+			continue
+		}
+		if line[0] == '[' && line[len(line)-1] == ']' {
+			inSection = line == "[Desktop Entry]"
+			continue
+		}
+		if !inSection {
+			continue
+		}
+		eq := strings.IndexByte(line, '=')
+		if eq < 0 {
+			continue
+		}
+		k, v := line[:eq], line[eq+1:]
+		switch k {
+		case "Name":
+			e.Name = v
+		case "Exec":
+			e.Exec = v
+		case "DesktopNames":
+			e.DesktopNames = v
+		case "Hidden":
+			e.Hidden = strings.EqualFold(v, "true")
+		case "NoDisplay":
+			e.NoDisplay = strings.EqualFold(v, "true")
+		}
+	}
+	if sc.Err() != nil {
+		return nil, sc.Err()
+	}
+	if e.Exec == "" {
+		return nil, fmt.Errorf("no Exec in %s", path)
+	}
+	if e.Name == "" {
+		e.Name = e.Exec
+	}
+	return e, nil
+}
+
+func ScanEnvs(xSessions, wlSessions, xScripts, wlScripts string, includeTTY bool) []PostLoginEnv {
+	var envs []PostLoginEnv
+
+	scanDesktopDir(xSessions, "x11", &envs)
+	scanDesktopDir(wlSessions, "wayland", &envs)
+	scanScriptDir(xScripts, "x11", &envs)
+	scanScriptDir(wlScripts, "wayland", &envs)
+
+	if len(envs) == 0 || includeTTY {
+		envs = append(envs, PostLoginEnv{Kind: "tty", Title: "TTYSHELL"})
+	}
+	return envs
+}
+
+func scanDesktopDir(dir, kind string, envs *[]PostLoginEnv) {
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		return
+	}
+	for _, e := range entries {
+		if e.IsDir() || filepath.Ext(e.Name()) != ".desktop" {
+			continue
+		}
+		path := filepath.Join(dir, e.Name())
+		de, err := parseDesktopEntry(path)
+		if err != nil || de.Hidden || de.NoDisplay {
+			continue
+		}
+		desktopNames, sessionDesktop := splitDesktopNames(de.DesktopNames, e.Name())
+		*envs = append(*envs, PostLoginEnv{
+			Kind:           kind,
+			Title:          de.Name,
+			XinitrcPath:    de.Exec,
+			ScriptPath:     de.Exec,
+			DesktopNames:   desktopNames,
+			SessionDesktop: sessionDesktop,
+		})
+	}
+}
+
+func splitDesktopNames(raw, fallback string) (currentDesktop, sessionDesktop string) {
+	if raw == "" {
+		return fallback, fallback
+	}
+	parts := strings.SplitN(raw, ";", 2)
+	sessionDesktop = strings.TrimSpace(parts[0])
+	currentDesktop = strings.ReplaceAll(raw, ";", ":")
+	return
+}
+
+func scanScriptDir(dir, kind string, envs *[]PostLoginEnv) {
+	entries, err := os.ReadDir(dir)
+	if err != nil {
+		return
+	}
+	for _, e := range entries {
+		if e.IsDir() {
+			continue
+		}
+		info, err := e.Info()
+		if err != nil {
+			continue
+		}
+		if info.Mode()&0111 == 0 {
+			continue
+		}
+		path := filepath.Join(dir, e.Name())
+		*envs = append(*envs, PostLoginEnv{
+			Kind:        kind,
+			Title:       e.Name(),
+			XinitrcPath: path,
+			ScriptPath:  path,
+		})
+	}
+}