Story: Add a default party per account with a quick-login checkbox

Add a default_party_id to the account entity, and a "Log in to default party" checkbox on the login dialog. When ticked (and the account has a default party set), login skips the PartyPickerDialog step entirely and calls select_party_request directly with the stored default, rather than making the user pick the same party from the list on every login. Also update the tenant/party provisioning scripts (e.g. projects/ores.shell/scripts/library/provisioning/barclays_system_provision.ores and the Acme/synthetic equivalent) to set the newly-provisioned party as the provisioning account's default, so freshly-provisioned environments come up ready for one-click login out of the box.

Every manual verification or screenshot-capture session currently repeats "log in, then pick the same single party from the list" every single time a service restart or environment ready-up happens — pure friction for the common single-tenant-per-checkout case this whole dev fleet uses. A stored default plus a quick-login checkbox removes a manual step from that sequence without removing the ability to switch parties when an account genuinely has more than one.

• Account entity gains a default_party_id field (nullable FK to party), across domain/SQL/repository/protocol layers.
• Login dialog shows a "Log in to default party" checkbox, enabled only when the account has a default party set.
• When ticked, login calls select_party_request directly with the stored default party, skipping PartyPickerDialog entirely.
• When unticked, or no default is set, login behaves exactly as today (party picker shown).
• The account can still switch parties after login (this only short-circuits the login-time picker step, not party-switching in general).
• barclays_system_provision.ores and the Acme/synthetic provisioning equivalent set the newly-provisioned party as the provisioning account's default, so freshly-provisioned environments come up ready for one-click login.

• default_party_id is a soft reference (no hard FK), matching the existing IAM/Refdata service-boundary separation — validated at the service layer (party membership check), not the database.
• Provisioning sets the default via an explicit new shell subcommand (accounts set-default-party) called from the recipes, rather than making provision party set it transparently — keeps "provision a party" and "make it my default" as two separately-visible, separately-testable steps.
• Reused ClientManager::selectParty() (client) and mirrored select_party's membership-check pattern (server) rather than adding parallel logic — the quick-login path and the manual picker path converge on the same call.
• Admin-side editing of the default party is a regular account field edit (combo box in the Parties tab → Save → change-reason → update_account_request → version history), the same as every other account field — not a separate immediate-write action. An earlier attempt at a parallel admin-scoped NATS endpoint plus a right-click "set default" menu was reworked after manual QA flagged it as inconsistent with the rest of the dialog (see the Result section of the login-dialog-checkbox task for the detail). The self-service set_my_default_party_request path (shell/provisioning) stayed as originally designed — it's a different kind of action (immediate self-service, like select_party), correctly not routed through Save.

• Per-tenant default parties (this is a per-account default, one party regardless of which tenant/context the account is used in).
• Removing or hiding PartyPickerDialog for accounts with multiple parties — the picker remains available whenever the checkbox is off or no default is set.

• projects/ores.qt/api/src/PartyPickerDialog.cpp — the dialog a default-party quick-login would bypass.
• projects/ores.qt/api/src/ClientManager.cpp — issues select_party_request after party selection; a default-party path would call this directly.
• projects/ores.shell/scripts/library/provisioning/barclays_system_provision.ores — the provisioning script to update to set the default party.