error-digest.ts: exclude genuine-bad-route 404s from mis-level (subnivelado) classifier

Daily error-digest false-flags benign 404s. isErrorShaped() in src/lib/error-digest.ts matches action=page_not_found because it contains the 'not_found' token in ERR_SHAPE_RX, so scanner/bad-route 404s (correctly info-tiered) show up in the 'Mal nivelados / subnivelado (logging bug)' section every day. Fix (bin-whey-diagnosed): early-return false for action==='page_not_found' before the regex. Drops page_not_found from both census + mis-level. Elazar-approved. App tiering already correct — classifier-only change. Mars/venus own copies flagged separately.