Sanitize file names taken from server metadata (closes #9)

A file title or album name decrypted from server data could name a path
outside the chosen directory (`../../.ssh/authorized_keys`). One module,
src/filename.ts, now makes such names safe for `quak get`/`get-thumb`
without `--out`, downloadFile/downloadThumbnail without outPath, and the
backup and metadata backup trees. Originals-cache extensions are limited to
letters and digits. A user-supplied path is still used as is. decryptFile
reads a missing or non-string title as "" and rejects metadata that is not
a JSON object.

Model: opus-5-5

src/cli-output.ts

@@ -9,6 +9,7 @@
 // `metadata.title`, and issue #52 requires that output stay byte-identical, so
 // the commands shape their output from the raw `EnteFile` through here.
 
+import { sanitizeFileName } from "./filename.js";
 import type { EnteFile, FileType, Microseconds } from "./model/types.js";
 
 // One row of `quak files --json`.
@@ -32,9 +33,11 @@ export const fileListRow = (file: EnteFile): FileListRow => ({
 export const fileListLine = (file: EnteFile): string =>
     `${file.id}\t${file.metadata.fileType}\t${file.metadata.title}`;
 
-// Default output path for `quak get` when `--out` is not given.
-export const originalName = (file: EnteFile): string => file.metadata.title;
+// Default output path for `quak get` when `--out` is not given. The title comes
+// from the server, so it is sanitized; `--out` is the user's and is used as is.
+export const originalName = (file: EnteFile): string =>
+    sanitizeFileName(file.metadata.title, `file-${file.id}`);
 
 // Default output path for `quak get-thumb` when `--out` is not given.
 export const thumbnailName = (file: EnteFile): string =>
-    `thumb_${file.metadata.title}`;
+    `thumb_${originalName(file)}`;