INFR: Complete adoption of the QEP-2 standard label set

[mmcky]

Problem

Repository labels diverge from the standard defined in QEP-2 (QuantEcon/qeps#2). As a software repository, QuantEcon.py takes the core 19 labels plus the software extension refactor — 20 labels.

The July 2026 tech-debt campaign created the labels it needed early (infrastructure, low-priority, security, good first issue, duplicate, wontfix) and renamed high priority → high-priority in place, so part of the standard set is now present. Remaining divergences:

Label	Uses	QEP-2 status
wishlist	6	❌ → low-priority plus a Type, or a Someday milestone
breaking	4	❌ → milestone, or a note in the body
performance	4	❌ → enhancement or refactor
tests	2	❌ on QEP-2's deliberately-not-labelled list → infrastructure/maintenance
CI	1	❌ → infrastructure or maintenance
beginner, in-work, ready, detailed-review, upstream	various	non-standard; review individually

Worth noting as a validation of the standard: refactor was already in active use here before QEP-2 — the label QEP-2 defines as the software extension is the one this repository independently reached for.

Sequencing

QEP-2 is Draft with a pilot-first adoption plan. This issue completes the alignment once the rollout reaches software repositories: run qe gh labels sync (additive; renames known variants in place so no history is lost), then a separate, deliberate qe gh labels prune pass reviewing each non-standard label one at a time.

Acceptance criteria

• Full sync applied once QEP-2 is Accepted and the rollout reaches software repos; all 20 labels present with standard colours and descriptions
• Each non-standard label reviewed individually under prune, with the decision recorded
• Existing issues re-labelled to exactly one Type each (overlaps with the backlog-triage issue)
• Any friction found is fed back to the QEP-2 thread as a field report

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From the July 2026 technical-debt audit (AI-assisted; claims verified against 28d4b3b on 2026-07-25).