fix(billing): send post-checkout users to the org billing page

[coopbri]

Summary

The Stripe checkout successUrl pointed at /workspaces/__SLUG__/settings, which is not a route in this scaffold (workspace and settings pages live under /organizations/$orgSlug/...). Any app scaffolded from this template redirected paying users to a Page Not Found immediately after subscribing.

Fix the root-cause scaffold so future apps do not inherit the 404: point successUrl at /organizations/__SLUG__/billing, which exists and shows the now-active subscription. Aether substitutes __SLUG__ with the real org slug before redirecting.

Matches the fix already shipped in fractal-app (#60); sibling apps (moment, blossom, arbor, channel, manifold, synapse) get the same fix in parallel.

Details

• Single-line change in src/components/pricing/PriceCard.tsx.
• In Aether's billing model the workspace is the organization, so the substituted __SLUG__ (the org slug) fills the /organizations/<slug>/... path correctly.
• Payment/subscription is unaffected; Stripe completes the subscription before the redirect. This only fixes the post-payment landing page.

Testing

• Pre-commit hooks pass: knip, biome check, tsc --noEmit.
• Verified /organizations/$orgSlug/billing route exists in the scaffold.