✨ Surface billing equivalences on the nav compute gauge #4349

Surface the configured billing.equivalences on the sidenav compute gauge.

Problem

The nav compute gauge (billing.navComputeGauge.component.vue) shows only raw remaining compute units + reset date (hover: "{remaining} remaining · resets {date}"). Raw units are opaque — a user can't tell what that remaining capacity means in practice.

Goal

Surface billing.equivalences as a human-readable capacity estimate in operation terms — e.g. "~N easy / ~M hard operations remaining" — derived from the equivalence ratios: remaining_units × plan.easyPerPeriod ÷ quota (same for hard). Render via the existing-but-unused BillingEquivalencesChipsComponent (kinds: easy / hard / feature).

Scope (billing module Vue, display-only)

• billing.navComputeGauge.component.vue — derive the easy/hard estimate from serverConfig.billing.equivalences + current meter remaining/quota.
• Wire the orphaned billing.equivalencesChips.component.vue (currently 0 imports) to render it.
• Config-driven → no-op when billing.equivalences is absent. No billing mechanism change (no meter/quota/reset logic touched).

Notes

• Generic enhancement — benefits any downstream consumer that defines per-plan equivalences in its config.

Created via /dev:issue