🔧 Config-source the upgrade-prompt pricing copy #4460

What — A shared upgrade-prompt component hardcodes one downstream project's specific product economics (grant size, pack price, plan names) instead of reading them from config.
Why — Any other downstream shows wrong pricing/marketing copy, and the public open-source devkit repo should not carry a specific consumer's product economics.

Scope — src/modules/billing/components/billing.upgradePrompt.component.vue (~L6-28) bakes literal product/pricing strings into the shared component (grant amount, pack price + CTA label, plan names) rather than sourcing them from billing.static-content.js / the static-content resolver, which is the documented single source of truth for pack/plan copy elsewhere in the module.

Fix: config-source every pricing/product literal in this component from the static-content resolver (config.billing.staticContent), matching the pattern already used by billing.subscriptions.component.vue; the devkit default copy must be generic/placeholder, not any real consumer's numbers.

Refs: internal audit cycle-1 2026-07-16 (M8).
Created via /dev:issue