Fix .bat anonymization, truncated-tree misses, submodule warning, account deletion (#742)

* fix: anonymize Windows batch scripts (#735)

mime-types maps .bat to application/x-msdownload, the same MIME type as
.exe/.dll, so batch scripts were classified as binary and streamed
through without any anonymization. Special-case .bat/.cmd as text before
the MIME lookup, keeping .exe/.dll binary.

* fix: recover files missing from truncated tree listings (#738)

GitHub truncates tree listings of very large repositories. Folders whose
listing was truncated are recorded in truncatedFolders, but files that
fell outside the listing never reached the database, so requesting them
returned 404 file_not_found even though they exist on GitHub — and a
force refresh could not help.

When a file lookup misses and its directory is under a truncated folder,
fetch the file metadata directly from GitHub's contents API (object
media type, so it works past the 1MB inline limit), cache it in the
database, and serve it normally.

* feat: warn when a repository uses git submodules (#737)

GitHub archives and tree listings never include submodule contents, so
submodules end up as empty folders in the anonymized repository, which
surprises users. Detect a root .gitmodules file and show a warning
banner in the explorer explaining that submodule contents are not
included.

* feat: allow users to delete their account (#741)

Add DELETE /api/user: removes all anonymized repositories, gists, and
pull requests owned by the user, best-effort revokes the GitHub OAuth
grant, and scrubs personal data (username, emails, tokens, GitHub id,
photo) from the user record. The record itself is kept with a
placeholder username so removed repoIds stay reserved and owner
references remain resolvable.

The settings page gains an Account section with a confirmed delete
button.

* fix: add missing error translations for token_expired and job_is_active

The error-code coverage test failed because both backend codes had no
frontend translation.

test/anonymized-file.test.js

@@ -219,3 +219,40 @@ describe("AnonymizedFile.isFileSupported()", function () {
       .false;
   });
 });
+
+// ---------------------------------------------------------------------------
+// Replicated logic from AnonymizedFile.recoverTruncatedFile (#738): a file
+// missing from the database is only recovered from GitHub when its directory
+// is under a folder whose tree listing was truncated.
+// ---------------------------------------------------------------------------
+
+function isUnderTruncatedFolder(fileDir, truncatedFolders) {
+  return truncatedFolders.some(
+    (folder) =>
+      folder === "" || fileDir === folder || fileDir.startsWith(folder + "/")
+  );
+}
+
+describe("AnonymizedFile truncated-folder matching (#738)", function () {
+  it("matches files directly inside a truncated folder", function () {
+    expect(isUnderTruncatedFolder("data", ["data"])).to.be.true;
+  });
+
+  it("matches files nested under a truncated folder", function () {
+    expect(isUnderTruncatedFolder("data/sub/dir", ["data"])).to.be.true;
+  });
+
+  it("matches everything when the root listing was truncated", function () {
+    expect(isUnderTruncatedFolder("", [""])).to.be.true;
+    expect(isUnderTruncatedFolder("any/dir", [""])).to.be.true;
+  });
+
+  it("does not match sibling folders sharing a prefix", function () {
+    expect(isUnderTruncatedFolder("database", ["data"])).to.be.false;
+    expect(isUnderTruncatedFolder("database/sub", ["data"])).to.be.false;
+  });
+
+  it("does not match when nothing was truncated", function () {
+    expect(isUnderTruncatedFolder("data", [])).to.be.false;
+  });
+});