Rewrite in Go: static binaries, zero runtime dependencies

Replace Node.js + Python codebase with three Go binaries:
- claude-statusline: CLI status bar for Claude Code
- claude-fetcher: standalone cron job for API usage
- claude-widget: system tray icon (fyne-io/systray + fogleman/gg)

All CGO-free for trivial cross-compilation. Add nfpm .deb packaging
with autostart and cron. CI pipeline produces Linux + Windows binaries,
.deb, .tar.gz, and .zip release assets.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/config/config.go

@@ -0,0 +1,93 @@
+package config
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"runtime"
+	"strings"
+)
+
+// WidgetConfig holds the widget configuration.
+type WidgetConfig struct {
+	RefreshInterval int    `json:"refresh_interval"`
+	OrgID           string `json:"org_id"`
+}
+
+var defaults = WidgetConfig{
+	RefreshInterval: 300,
+	OrgID:           "",
+}
+
+// ConfigDir returns the platform-specific config directory.
+func ConfigDir() string {
+	if v := os.Getenv("CLAUDE_STATUSLINE_CONFIG"); v != "" {
+		return v
+	}
+	if runtime.GOOS == "windows" {
+		return filepath.Join(os.Getenv("LOCALAPPDATA"), "claude-statusline")
+	}
+	if xdg := os.Getenv("XDG_CONFIG_HOME"); xdg != "" {
+		return filepath.Join(xdg, "claude-statusline")
+	}
+	home, _ := os.UserHomeDir()
+	return filepath.Join(home, ".config", "claude-statusline")
+}
+
+// ConfigPath returns the path to widget-config.json.
+func ConfigPath() string {
+	return filepath.Join(ConfigDir(), "widget-config.json")
+}
+
+// SessionKeyPath returns the path to the session-key file.
+func SessionKeyPath() string {
+	return filepath.Join(ConfigDir(), "session-key")
+}
+
+// Load reads widget-config.json and merges with defaults.
+func Load() WidgetConfig {
+	cfg := defaults
+	data, err := os.ReadFile(ConfigPath())
+	if err != nil {
+		return cfg
+	}
+	_ = json.Unmarshal(data, &cfg)
+	if cfg.RefreshInterval < 60 {
+		cfg.RefreshInterval = 60
+	}
+	return cfg
+}
+
+// Save writes widget-config.json.
+func Save(cfg WidgetConfig) error {
+	dir := ConfigDir()
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		return err
+	}
+	data, err := json.MarshalIndent(cfg, "", "  ")
+	if err != nil {
+		return err
+	}
+	return os.WriteFile(ConfigPath(), data, 0o644)
+}
+
+// GetSessionKey returns the session key from env or file.
+func GetSessionKey() string {
+	if v := os.Getenv("CLAUDE_SESSION_KEY"); v != "" {
+		return strings.TrimSpace(v)
+	}
+	data, err := os.ReadFile(SessionKeyPath())
+	if err != nil {
+		return ""
+	}
+	return strings.TrimSpace(string(data))
+}
+
+// SetSessionKey writes the session key to file.
+func SetSessionKey(key string) error {
+	dir := ConfigDir()
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		return err
+	}
+	return os.WriteFile(SessionKeyPath(), []byte(strings.TrimSpace(key)+"\n"), 0o600)
+}