Parse labeled series numbers above 999

[justadityaraj]

Brief summary

Parse labeled series sequence numbers above 999 without changing how unlabeled four-digit prefixes are interpreted.

Which issue is fixed?

Related to #4781 and #5103.

In-depth Description

Problem / Context

The folder parser limits every series sequence to three digits. As a result, documented labels such as Vol 1456 are not recognized, even though a label makes the value unambiguous and was recommended as the workaround for four-digit sequences. The remaining folder text is then parsed into the wrong metadata fields.

Changes

• Allow labeled Vol, Volume, and Book sequences to contain more than three digits.
• Keep the existing three-digit limit for unlabeled sequences so a prefix such as 1456 - Title continues to be treated as a publication year.
• Add regression coverage for both behaviors.

User impact

Libraries with long-running serials can use an explicit label and have the sequence, publication year, and title scanned into the correct fields. Existing unlabeled year-based folder names keep their current meaning.

How have you tested this?

Verification

• The new labeled-sequence regression failed against upstream/master before the parser change and passes afterward.
• npx mocha test/server/utils/scandir.test.js — 3 passing.
• npm test — 356 passing.
• git diff --check — passed.

Screenshots

N/A — server-side folder metadata parsing only.