fix: make RDP drive redirection writable on the stock deployment (#1333)

* fix: make RDP drive redirection writable on the stock deployment

The default drive-path was /drive on the guacd side, which the official
guacd image cannot create as its non-root user, so every upload was
refused with guacd's raw "FAIL (CANNOT OPEN)" ack. Default to
GUACD_DRIVE_PATH (set to the shared termix-data volume in compose) with
one folder per user, and explain guacd's refusal in the file browser.

* style: format RDP drive settings

src/ui/features/guacamole/GuacamoleFileBrowser.tsx

@@ -19,6 +19,7 @@ import {
   parentPath,
   saveBlobAs,
   uploadFile,
+  describeUploadError,
   type RemoteFileEntry,
 } from "./guacamole-filesystem.ts";
 
@@ -76,9 +77,9 @@ export function GuacamoleFileBrowser({
           toast.success(t("guacamole.files.uploaded", { name: file.name }));
         } catch (err) {
           toast.error(
-            err instanceof Error
-              ? err.message
-              : t("guacamole.files.uploadFailed", { name: file.name }),
+            describeUploadError(err, (key) =>
+              t(`guacamole.files.${key}`, { name: file.name }),
+            ),
           );
         } finally {
           setBusyName(null);

src/ui/features/guacamole/guacamole-filesystem.test.ts

@@ -0,0 +1,20 @@
+import { describe, expect, it } from "vitest";
+import { describeUploadError } from "./guacamole-filesystem";
+
+const t = (key: string) => `#${key}`;
+
+describe("describeUploadError", () => {
+  it("explains guacd's refusal to open the target file as a drive-folder problem", () => {
+    expect(describeUploadError(new Error("FAIL (CANNOT OPEN)"), t)).toBe(
+      "#driveNotWritable",
+    );
+    expect(describeUploadError(new Error("FAIL (NO FS)"), t)).toBe(
+      "#driveUnavailable",
+    );
+  });
+
+  it("passes other messages through and falls back for unknown errors", () => {
+    expect(describeUploadError(new Error("disk full"), t)).toBe("disk full");
+    expect(describeUploadError(undefined, t)).toBe("#uploadFailed");
+  });
+});

src/ui/features/guacamole/guacamole-filesystem.ts

@@ -163,3 +163,22 @@ export function saveBlobAs(blob: Blob, filename: string): void {
   link.click();
   URL.revokeObjectURL(url);
 }
+
+/**
+ * Turns an upload failure into something a user can act on. guacd answers a
+ * refused stream with an ack like "FAIL (CANNOT OPEN)" - accurate, but it
+ * means "the drive folder isn't writable", which is what people need to hear.
+ */
+export function describeUploadError(
+  error: unknown,
+  t: (key: "driveNotWritable" | "driveUnavailable" | "uploadFailed") => string,
+): string {
+  const message = error instanceof Error ? error.message : "";
+  if (/cannot open|can't open|permission denied/i.test(message)) {
+    return t("driveNotWritable");
+  }
+  if (/no fs/i.test(message)) {
+    return t("driveUnavailable");
+  }
+  return message || t("uploadFailed");
+}