feat: add Gemini skill integration and multi-user AI setup

gui/tabs/setup_tab.py

@@ -14,6 +14,7 @@ from core.claude_setup import (
     install_all,
     install_claude_skill,
     install_codex_skill,
+    install_gemini_skill,
     install_ssh_script,
 )
 from core.i18n import t
@@ -63,6 +64,8 @@ class SetupTab(ctk.CTkFrame):
             ("claude_skill_installed", "status_claude_skill"),
             ("codex_skill_installed", "status_codex_skill"),
             ("codex_wrapper_installed", "status_codex_wrapper"),
+            ("gemini_skill_installed", "status_gemini_skill"),
+            ("gemini_wrapper_installed", "status_gemini_wrapper"),
             ("ssh_key_exists", "status_ssh_key"),
         ]
         for key, i18n_key in status_items:
@@ -112,6 +115,12 @@ class SetupTab(ctk.CTkFrame):
         )
         self.codex_skill_btn.pack(side="left", padx=5)
 
+        self.gemini_skill_btn = make_icon_button(
+            top_btn_row, "confirm", t("install_gemini_skill"), width=130, fg_color="#6b7280",
+            command=self._install_gemini_skill
+        )
+        self.gemini_skill_btn.pack(side="left", padx=5)
+
         bottom_btn_row = ctk.CTkFrame(ind_frame, fg_color="transparent")
         bottom_btn_row.pack(fill="x")
 
@@ -370,6 +379,11 @@ class SetupTab(ctk.CTkFrame):
         self._log(msg)
         self._refresh_status()
 
+    def _install_gemini_skill(self):
+        msg = install_gemini_skill()
+        self._log(msg)
+        self._refresh_status()
+
     def _install_skill(self):
         msg = install_claude_skill()
         self._log(msg)