v1.8.52: icons module, Windows SSH sanitization, embedded RDP improvements, UI polish

- Add core/icons.py — centralized icon text helper with emoji/symbol support
- Add Windows SSH command sanitization in ssh.py (Linux→Windows auto-translation)
- Improve embedded RDP: launch tab connect/disconnect, fullscreen toggle
- Refactor sidebar: cleaner server type badges
- Update server_dialog: adaptive fields per server type
- Add setup_openssh.bat tool
- Update skill-ssh.md and CLAUDE.md docs for Windows SSH support
- Cleanup old releases, add v1.8.48-v1.8.52

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

gui/widgets/status_badge.py

@@ -9,6 +9,7 @@ COLORS = {
     "offline": "#ef4444",  # red
     "unknown": "#6b7280",  # gray
     "disabled": "#9ca3af", # light gray
+    "checking": "#f59e0b", # yellow
 }
 
 
@@ -24,5 +25,10 @@ class StatusBadge(ctk.CTkLabel):
 
     def _update_color(self):
         color = COLORS.get(self._status, COLORS["unknown"])
-        symbol = "\u2014" if self._status == "disabled" else "\u25cf"
+        if self._status == "disabled":
+            symbol = "\u2014"     # —
+        elif self._status == "checking":
+            symbol = "\u25d0"     # ◐
+        else:
+            symbol = "\u25cf"     # ●
         self.configure(text=symbol, text_color=color, font=("", 14))