workflow-fix: widen check-28 figure token pattern to arm slugs

Overview / Motivation

Auto-filed from a prose follow-up surfaced by clean-result-critic on task #1768 (fold-round review, 2026-08-02).

Goal

Widen verify_task_body.py check 28 (check_figure_label_codes) token pattern to catch hyphen-separated arm slugs (e.g. cas-pers-con-lr1e5-s137) rendered on figure tick labels, WARN once per body (not per figure).

Workflow gap

• Bug observed: check 28 caught M_0 in a rendered figure but missed hyphen-separated arm slugs on tick labels across ~10 figures of #1768's folded body; only 4 captions decode them.
• Why it is a workflow gap: the opaque-code lens (no-opaque-condition-codes policy) has a mechanical scanner whose token pattern covers math-ish tokens but not the fleet's slug grammar — a real Lens 3 blind spot.
• Confidence (emitter): medium
• verified-at-filing: grep -n "opaque\|check_figure" scripts/verify_task_body.py → check 28 = check_figure_label_codes (doc L518-520, "must not carry opaque [codes]", WARN class) exists and is the correct target; slug-shaped tokens absent from its pattern per the critic's live read (2026-08-02).

Proposed change (candidate diff sketch — refine in planning)

diff_sketch: | In check_figure_label_codes: add a slug token alternation r"\b[a-z]{2,4}(?:-[a-z0-9]{1,12}){2,}\b" (behavior-context-regime-lr-seed grammar), deduped to ONE WARN per body listing offending figures; captions that decode the slugs suppress the WARN for that figure.

Scope / surfaces

• Primary target: scripts/verify_task_body.py (+ tests). Nearest sibling check 29 (figures tracked at HEAD) untouched.

Constraints / invariants

• WARN-class only (never a new hard FAIL on grandfathered bodies); workflow-surface only.
• Recursion guard applies (EPM_WORKFLOW_FIX_SESSION=1 + workflow_fix_target line).

Provenance

• workflow_fix_target: scripts/verify_task_body.py
• fingerprint: 68dcc4ea7de6 Verbatim surfaced prose: "verify_task_body.py check 28's figure-text scanner caught M_0 but misses hyphen-separated arm slugs (cas-pers-con-lr1e5-s137) on tick labels — widening the token pattern (WARN once per body, not per figure) closes a real Lens 3 blind spot."