Add Provider Install wizard to GUI

- Create ProviderInstallDialog for installing AI provider CLI tools
- Shows available providers (Claude, Codex, Gemini, OpenCode, Ollama)
- Detects which providers are already installed
- Runs installation commands with live output
- Offers to add provider variants after installation
- Add "Tools" menu with "Install AI Provider..." option
- Add "Install Provider..." button to Providers page

Co-Authored-By: Claude Opus 4.5 <[email protected]>

src/cmdforge/gui/pages/providers_page.py

@@ -35,7 +35,13 @@ class ProvidersPage(QWidget):
 
         header_layout.addStretch()
 
+        self.btn_install = QPushButton("Install Provider...")
+        self.btn_install.setToolTip("Install a new AI provider CLI tool")
+        self.btn_install.clicked.connect(self._install_provider)
+        header_layout.addWidget(self.btn_install)
+
         self.btn_add = QPushButton("Add Provider")
+        self.btn_add.setToolTip("Manually add a provider configuration")
         self.btn_add.clicked.connect(self._add_provider)
         header_layout.addWidget(self.btn_add)
 
@@ -121,6 +127,14 @@ class ProvidersPage(QWidget):
         name_item = self.table.item(row, 0)
         return name_item.text(), name_item.data(Qt.UserRole)
 
+    def _install_provider(self):
+        """Open the provider installation wizard."""
+        from ..dialogs.provider_install_dialog import ProviderInstallDialog
+        dialog = ProviderInstallDialog(self)
+        if dialog.exec():
+            self.refresh()
+            self.main_window.show_status("Providers updated")
+
     def _add_provider(self):
         """Add a new provider."""
         from ..dialogs.provider_dialog import ProviderDialog