feat(integrations): add Git hosting integrations and repo listing

Add support for integrating with external Git hosts (GitLab, Gitea,
and Azure DevOps). The backend gains a client to fetch paginated
repository lists, normalise base URLs, and surface provider errors.
Credentials are loaded from the OS keychain and a Tauri command is
exposed for the frontend to list integration repositories.

- Implement integration client with pagination, deserialization,
  and provider-specific handling.
- Centralise keychain credential loading and expose listing command.
- Update UI to manage integration metadata, persist settings, and
  save/remove tokens to the OS keychain for cloning and operations.

src/lib/components/AppSettingsDialog.svelte

@@ -6,11 +6,13 @@
     ChevronDown,
     ChevronRight,
     CircleDashed,
+    CloudCog,
     Code2,
     FolderOpen,
     GitCompare,
     GitMerge,
     Languages,
+    KeyRound,
     Palette,
     RefreshCw,
     RotateCw,
@@ -29,6 +31,7 @@
     type ExternalToolKind,
     type ExternalToolPreset,
   } from "../externalTools";
+  import { configuredIntegrationCount, defaultGitIntegrationSettings } from "../integrations";
   import type {
     AnalyticsSettings,
     AppAppearance,
@@ -37,11 +40,14 @@
     CustomThemeColors,
     DetectedExternalTool,
     ExternalToolsSettings,
+    GitIntegrationSecretUpdate,
+    GitIntegrationSettings,
     ToolOpenMode,
   } from "../types";
+  import IntegrationSettingsPage from "./IntegrationSettingsPage.svelte";
   import SelectMenu from "./SelectMenu.svelte";
 
-  type SettingsPage = "general" | "tools";
+  type SettingsPage = "general" | "integrations" | "tools";
 
   interface Props {
     analytics: AnalyticsSettings;
@@ -51,11 +57,12 @@
     language: AppLanguage;
     autoRefresh: boolean;
     externalTools: ExternalToolsSettings;
+    integrations: GitIntegrationSettings;
     detectedTools: DetectedExternalTool[];
     detectionPending: boolean;
     detectionUnavailable: boolean;
     onRefreshDetectedTools: () => void | Promise<void>;
-    onSave: (settings: AnalyticsSettings, theme: AppTheme, appearance: AppAppearance, customTheme: CustomThemeColors, language: AppLanguage, autoRefresh: boolean, externalTools: ExternalToolsSettings) => void;
+    onSave: (settings: AnalyticsSettings, theme: AppTheme, appearance: AppAppearance, customTheme: CustomThemeColors, language: AppLanguage, autoRefresh: boolean, externalTools: ExternalToolsSettings, integrations: GitIntegrationSettings, integrationSecrets: GitIntegrationSecretUpdate[]) => void | Promise<void>;
     onClose: () => void;
   }
 
@@ -67,6 +74,7 @@
     language = "en",
     autoRefresh = true,
     externalTools,
+    integrations,
     detectedTools = [],
     detectionPending = false,
     detectionUnavailable = false,
@@ -77,7 +85,7 @@
 
   const toolKinds: ExternalToolKind[] = ["editor", "diff", "merge", "terminal", "fileManager"];
 
-  let activePage = $state<SettingsPage>("tools");
+  let activePage = $state<SettingsPage>("integrations");
   let activeToolKind = $state<ExternalToolKind>("editor");
   let advancedOpen = $state(false);
   let analyticsEnabled = $state(true);
@@ -87,6 +95,9 @@
   let selectedLanguage = $state<AppLanguage>("en");
   let autoRefreshEnabled = $state(true);
   let tools = $state<ExternalToolsSettings>(defaultExternalToolsSettings());
+  let integrationDraft = $state<GitIntegrationSettings>(defaultGitIntegrationSettings());
+  let integrationSecretUpdates = $state<GitIntegrationSecretUpdate[]>([]);
+  let saving = $state(false);
   const isGerman = $derived(selectedLanguage === "de");
 
   $effect(() => {
@@ -97,14 +108,21 @@
     selectedLanguage = language;
     autoRefreshEnabled = autoRefresh;
     tools = structuredClone(externalTools);
+    integrationDraft = structuredClone(integrations);
   });
 
-  function save() {
-    onSave({
-      ...analytics,
-      enabled: analyticsEnabled,
-      noticeSeen: true,
-    }, selectedTheme, selectedAppearance, $state.snapshot(customColors), selectedLanguage, autoRefreshEnabled, $state.snapshot(tools));
+  async function save() {
+    if (saving) return;
+    saving = true;
+    try {
+      await onSave({
+        ...analytics,
+        enabled: analyticsEnabled,
+        noticeSeen: true,
+      }, selectedTheme, selectedAppearance, $state.snapshot(customColors), selectedLanguage, autoRefreshEnabled, $state.snapshot(tools), $state.snapshot(integrationDraft), $state.snapshot(integrationSecretUpdates));
+    } finally {
+      saving = false;
+    }
   }
 
   function resetCustomColors() {
@@ -315,10 +333,22 @@
             </span>
             {#if !detectionUnavailable}<em>{detectedTools.length}</em>{/if}
           </button>
+          <button type="button" class:active={activePage === "integrations"} onclick={() => { activePage = "integrations"; }}>
+            <CloudCog size={16} aria-hidden="true" />
+            <span>
+              <strong>{isGerman ? "Integrationen" : "Integrations"}</strong>
+              <small>GitLab, Azure DevOps & Gitea</small>
+            </span>
+            <em>{configuredIntegrationCount(integrationDraft)}</em>
+          </button>
 
           <div class="settings-nav-note">
-            <ShieldCheck size={15} aria-hidden="true" />
-            <p>{isGerman ? "Tool-Argumente werden direkt und ohne zusätzliche Shell übergeben." : "Tool arguments are passed directly without an extra shell."}</p>
+            {#if activePage === "integrations"}<KeyRound size={15} aria-hidden="true" />{:else}<ShieldCheck size={15} aria-hidden="true" />{/if}
+            <p>
+              {activePage === "integrations"
+                ? (isGerman ? "Tokens werden sicher im Schlüsselbund des Betriebssystems gespeichert." : "Tokens are stored securely in the operating system keychain.")
+                : (isGerman ? "Tool-Argumente werden direkt und ohne zusätzliche Shell übergeben." : "Tool arguments are passed directly without an extra shell.")}
+            </p>
           </div>
         </nav>
 
@@ -399,7 +429,7 @@
                 </label>
               </section>
             </div>
-          {:else}
+          {:else if activePage === "tools"}
             <div class="settings-page-head tools-page-head">
               <div>
                 <h3>{isGerman ? "Externe Tools" : "External tools"}</h3>
@@ -518,6 +548,19 @@
                 </div>
               {/if}
             </section>
+          {:else}
+            <div class="settings-page-head">
+              <div>
+                <h3>{isGerman ? "Integrationen" : "Integrations"}</h3>
+                <p>{isGerman ? "Verbinde Gitty mit deinen Git-Hosting-Diensten." : "Connect Gitty to your Git hosting services."}</p>
+              </div>
+            </div>
+            <IntegrationSettingsPage
+              language={selectedLanguage}
+              settings={integrationDraft}
+              onChange={(next) => { integrationDraft = next; }}
+              onSecretsChange={(updates) => { integrationSecretUpdates = updates; }}
+            />
           {/if}
         </div>
       </div>
@@ -526,7 +569,7 @@
         <span>{isGerman ? "Änderungen werden erst beim Speichern übernommen." : "Changes are applied only after saving."}</span>
         <div>
           <button class="btn-secondary" type="button" onclick={onClose}>{isGerman ? "Abbrechen" : "Cancel"}</button>
-          <button class="btn-primary" type="submit"><Check size={16} aria-hidden="true" />{isGerman ? "Änderungen speichern" : "Save changes"}</button>
+          <button class="btn-primary" type="submit" disabled={saving}><Check size={16} aria-hidden="true" />{saving ? (isGerman ? "Wird gespeichert…" : "Saving…") : (isGerman ? "Änderungen speichern" : "Save changes")}</button>
         </div>
       </footer>
     </form>
@@ -663,7 +706,8 @@
     .app-settings-head { min-height: 58px; padding: 10px 12px; }
     .app-settings-mark { width: 34px; height: 34px; }
     .settings-nav button small, .settings-nav button em { display: none; }
-    .settings-nav > button { grid-template-columns: auto minmax(0, 1fr); }
+    .settings-nav > button { grid-template-columns: auto minmax(0, 1fr); gap: 5px; padding-inline: 6px; }
+    .settings-nav button strong { font-size: 10px; }
     .settings-page-head { align-items: stretch; flex-direction: column; }
     .tool-rescan-button { align-self: flex-start; }
     .general-settings-grid { grid-template-columns: 1fr; }