feat(shortcuts): Add Ctrl/Cmd+1..4 to switch main views

Add keyboard shortcuts (Ctrl/Cmd + 1–4) to jump to the four main views:
Dashboard, Repositories, Pull Requests and Issues & Boards.

- Handler runs in the capture phase so editors/dialogs can still trap keys.
- Switching is blocked when the app is busy or any modal/overlay is open; repeats
  and combinations with Alt/Shift are ignored.
- When switching to the repository view the shortcut selects an existing repo
  tab (it will not open a native file dialog if no repo is available).

Also update tab button titles to surface the shortcuts and add entries to the
help overlay (English and German).

src/App.svelte

@@ -5940,6 +5940,67 @@
 
   // ── Event handlers ─────────────────────────────────────────────────────────
 
+  // ── Main view shortcuts ────────────────────────────────────────────────────
+  // Ctrl/Cmd + 1…4 jump to the four main views in the order of the tab bar.
+  const mainViewShortcuts: AppView[] = ["management", "repository", "review-center", "issues"];
+
+  function mainViewShortcutIndex(event: KeyboardEvent): number {
+    if (!(event.ctrlKey || event.metaKey) || event.altKey || event.shiftKey) return 0;
+    const code = event.code ?? "";
+    const digit = code.startsWith("Digit")
+      ? Number(code.slice(5))
+      : code.startsWith("Numpad")
+        ? Number(code.slice(6))
+        : Number(event.key);
+    if (!Number.isInteger(digit) || digit < 1 || digit > mainViewShortcuts.length) return 0;
+    return digit;
+  }
+
+  // Capture phase: dialogs and editors trap keys on their own nodes, and the
+  // view shortcut must not depend on the event reaching window afterwards.
+  function handleViewShortcutKeydown(event: KeyboardEvent) {
+    const index = mainViewShortcutIndex(event);
+    if (index === 0) return;
+    if (import.meta.env.DEV) {
+      console.debug("[gitty] view shortcut", { key: event.key, code: event.code, index, blocked: mainViewSwitchBlocked(), activeView });
+    }
+    event.preventDefault();
+    if (!event.repeat) switchMainView(index);
+  }
+
+  // Anything modal owns the keyboard, so the view stays where it is.
+  function mainViewSwitchBlocked(): boolean {
+    return isBusy
+      || commandPaletteOpen || helpOpen || globalSearchOpen || appSettingsOpen
+      || cloneDialogOpen || initRepositoryDialogOpen || credDialogOpen
+      || compareDialogOpen || compareSelectOpen || fileHistoryDialogOpen
+      || resolveDialogOpen || interactiveRebaseOpen || reflogOpen || bisectOpen
+      || worktreeDialogOpen || submoduleDialogOpen || gitLfsDialogOpen
+      || linePatchOpen || aiReviewOpen
+      || pendingSubmoduleInitialization !== null || pendingDiscard !== null
+      || newBranchCommit !== null || renameBranchTarget !== null
+      || deleteBranchTarget !== null || commitNoteTarget !== null;
+  }
+
+  function switchMainView(index: number) {
+    if (mainViewSwitchBlocked()) return;
+    const view = mainViewShortcuts[index - 1];
+    if (!view || view === activeView) return;
+    closeRepoTabContextMenu();
+    if (view === "management") {
+      openRepoManagement();
+    } else if (view === "review-center") {
+      openReviewCenter();
+    } else if (view === "issues") {
+      activeView = "issues";
+    } else {
+      // Without an open repository the tab bar would ask for a folder; a
+      // keyboard shortcut should never pop up a native file dialog.
+      const path = repoTabs.find((tab) => sameRepoPath(tab.path, activeRepoPath))?.path ?? repoTabs[0]?.path;
+      if (path) void selectRepoTab(path);
+    }
+  }
+
   function handleWindowKeydown(event: KeyboardEvent) {
     if ((event.ctrlKey || event.metaKey) && event.key.toLowerCase() === "k") {
       event.preventDefault();
@@ -5992,7 +6053,7 @@
   <title>Gitty</title>
 </svelte:head>
 
-<svelte:window on:click={handleWindowClick} on:keydown={handleWindowKeydown} on:contextmenu|capture={handleWindowContextMenu} />
+<svelte:window on:click={handleWindowClick} on:keydown|capture={handleViewShortcutKeydown} on:keydown={handleWindowKeydown} on:contextmenu|capture={handleWindowContextMenu} />
 
 {#if sidebarSectionMenu && activeView === "repository"}
   <SidebarSectionMenu x={sidebarSectionMenu.x} y={sidebarSectionMenu.y} language={appLanguage}