feat: add input/checkbox to confirm dialog and multi-selection actions

Introduce richer confirmation dialogs and wire them through the UI so actions
can collect an optional single-line input and a checkbox option.

- ConfirmDialog: support optional input and checkbox (with defaultChecked),
  expose onConfirm(result: {checked, value}). Focus/selects input when present
  and blocks confirm while required inputs/checkboxes are missing.
- App: add askConfirmation(...) returning {confirmed, value, checked} and keep
  requestConfirmation(...) as a convenience boolean wrapper. Update answer flow
  to pass the full result. Use the new prompt in stashStatusFiles to collect a
  stash message and "include untracked" option before saving.
- Status/Explorer/Worktree: add multi-selection support for stop-tracking and
  stash operations. onStopTracking now accepts an array of paths and a new
  "selection" kind; status context menu shows selection counts and uses a
  CopyCheck icon for selections. Added corresponding i18n messages.

This change keeps existing UX but enables collecting extra confirmation data
and acting on multi-file selections.

src/App.svelte

@@ -438,8 +438,9 @@
   let externalToolsDetectionUnavailable = false;
   let errorMessage = "";
   let operation = "";
+  type ConfirmAnswer = { confirmed: boolean; value: string; checked: boolean };
   let confirmDialogRequest: ConfirmRequest | null = null;
-  let confirmDialogResolve: ((confirmed: boolean) => void) | null = null;
+  let confirmDialogResolve: ((answer: ConfirmAnswer) => void) | null = null;
   let compareFrom = "";
   let compareTo = "";
   let comparison: GitCommitComparison | null = null;
@@ -1289,15 +1290,20 @@
     setLanguage(next);
   }
 
-  /** Show the confirmation dialog and resolve once the user answers. */
-  function requestConfirmation(request: ConfirmRequest): Promise<boolean> {
-    confirmDialogResolve?.(false);
+  /** Show the dialog and resolve with the answer, including input and checkbox. */
+  function askConfirmation(request: ConfirmRequest): Promise<ConfirmAnswer> {
+    confirmDialogResolve?.({ confirmed: false, value: "", checked: false });
     confirmDialogRequest = request;
-    return new Promise<boolean>((resolve) => {
+    return new Promise<ConfirmAnswer>((resolve) => {
       confirmDialogResolve = resolve;
     });
   }
 
+  /** Yes/no only, for the many confirmations that need nothing else. */
+  async function requestConfirmation(request: ConfirmRequest): Promise<boolean> {
+    return (await askConfirmation(request)).confirmed;
+  }
+
   /** Confirmation shown before deleting a local or remote branch. */
   function branchDeleteConfirmRequest(branch: GitBranchInfo, force: boolean): ConfirmRequest {
     const remoteName = branch.remote ? branch.name.split("/")[0] : "";
@@ -1356,11 +1362,11 @@
     };
   }
 
-  function answerConfirmation(confirmed: boolean) {
+  function answerConfirmation(confirmed: boolean, value = "", checked = false) {
     const resolve = confirmDialogResolve;
     confirmDialogRequest = null;
     confirmDialogResolve = null;
-    resolve?.(confirmed);
+    resolve?.({ confirmed, value, checked });
   }
 
   function applyThemePreference(next: AppTheme) {
@@ -4797,8 +4803,34 @@
   }
 
   async function stashStatusFiles(files: GitFileStatus[], label: string) {
-    const suffix = files.length === 1 ? files[0].path : `${label} (${files.length} files)`;
-    await saveStash(`Gitty: ${suffix}`, true, files);
+    if (files.length === 0) return;
+    const suffix = files.length === 1
+      ? files[0].path
+      : label ? `${label} (${files.length} files)` : `${files.length} files`;
+    const fallbackMessage = `Gitty: ${suffix}`;
+
+    const answer = await askConfirmation({
+      eyebrow: t("confirm.stashFiles.eyebrow"),
+      title: files.length === 1 ? t("confirm.stashFiles.titleOne") : t("confirm.stashFiles.title", { count: files.length }),
+      message: t("confirm.stashFiles.message"),
+      items: files.map((file) => file.path),
+      input: {
+        label: t("confirm.stashFiles.inputLabel"),
+        placeholder: fallbackMessage,
+        value: fallbackMessage,
+        optional: true,
+      },
+      checkbox: {
+        label: t("confirm.stashFiles.untracked"),
+        note: t("confirm.stashFiles.untrackedNote"),
+        defaultChecked: true,
+      },
+      confirmLabel: t("stashes.save"),
+      danger: false,
+    });
+
+    if (!answer.confirmed) return;
+    await saveStash(answer.value.trim() || fallbackMessage, answer.checked, files);
   }
 
   async function applyStashEntry(stash: GitStash) {
@@ -4884,12 +4916,13 @@
     });
   }
 
-  async function stopTrackingTarget(target: string, kind: "file" | "folder") {
-    if (!activeRepoPath || !target) return;
+  async function stopTrackingTarget(targets: string[], kind: "file" | "folder" | "selection") {
+    const paths = targets.filter(Boolean);
+    if (!activeRepoPath || paths.length === 0) return;
     await runOperation(`Stopping tracking for ${kind}`, async () => {
-      applyStatus(await untrackPaths(activeRepoPath, [target]));
+      applyStatus(await untrackPaths(activeRepoPath, paths));
       await refreshExplorerFiles(activeRepoPath);
-      trackEvent("git_paths_untracked", { kind });
+      trackEvent("git_paths_untracked", { kind, paths: paths.length });
     });
   }
 
@@ -6608,7 +6641,7 @@
 {#if confirmDialogRequest}
   <ConfirmDialog
     request={confirmDialogRequest}
-    onConfirm={() => answerConfirmation(true)}
+    onConfirm={(result) => answerConfirmation(true, result.value, result.checked)}
     onCancel={() => answerConfirmation(false)}
   />
 {/if}