feat(payment): regional pricing, Stripe price id, OAuth domain (→ staging)

[rdahis]

Warning

Do not merge until staging has been reset to main.
Merging now conflicts, because staging still carries these same changes under their
original SHAs. After the reset this applies cleanly.

Reconstructs the payment/account work onto main.

These commits were originally pushed to staging under the old workflow. staging is
scheduled to be reset to main, so they have been cherry-picked onto a branch cut from
main per the current Git Flow.

What's here

• feat: expose the Stripe price id on StripePriceNode #1044 expose the Stripe price id on StripePriceNode
• fix(account): return Google OAuth to the originating frontend domain #1046 return Google OAuth to the originating frontend domain
• feat(payment): charge card-country regional price at checkout #1045 charge the card-country regional price at checkout (trial path)
• refactor(account): remove legacy Career.team_old and role_old fields #1048 remove legacy Career.team_old / role_old

Two further staging-only commits (the convert_form_field graphql fix and #1038 spatial
coverage) are already on main under different SHAs — cherry-picking them came out empty,
so they are correctly omitted.

Heads-up for the deploy

• Carries a migration: account/0029_remove_career_team_old_remove_career_role_old — it
  drops two columns. Chain is intact; its dependency 0028_alter_account_uuid is already on main.
• main does not yet have the product-aware webhook refactor that exists on staging. The
  regional-pricing hook applied cleanly into setup_intent_succeeded, but CI (especially
  test_regional_pricing.py) is the real check, since a clean cherry-pick is textual, not semantic.
• Enforcement fails safe by design: on any uncertainty it keeps the original price rather than
  blocking checkout.

Deploy order

Merge and deploy before the website PR of the same name.

[mergify]

⚠️ The sha of the head commit of this PR conflicts with #1057. Mergify cannot evaluate rules on this PR. Once #1057 is merged or closed, Mergify will resume processing this PR. ⚠️

[rdahis]

Closing — not needed.

These changes are already present in staging under their original SHAs; this branch is a
reconstruction of that same work onto main for the new Git Flow. Merging here would have
changed only CLAUDE.md (an earlier note on this PR said it would conflict — that was wrong
for this repo; it would have been a near-no-op).

staging is being reset to main shortly and will pick these up from main at that point.

#1057 (→ main) stays open and is the one that matters. The branch is not deleted by
closing this.