feat(egress): report loyalty milestones unlocked by a purchase

[dinosoeren]

Adds unlocked_milestones to the egress PlayerLoyaltyState, so a purchase request reports which loyalty milestones that purchase's points gain crossed. Milestones can be claimed at any time rather than being granted automatically when they are reached, so the moment a milestone becomes available is otherwise not observable from the purchase payload.

• repeated Milestone unlocked_milestones = 10 on PlayerLoyaltyState, reusing the message's existing nested Milestone shape (milestone_id plus its rewards), so no new vocabulary is introduced.
• Purely additive: the field is absent whenever the purchase crossed no threshold, so existing payloads are unchanged.
• A single purchase can cross more than one threshold, so this is repeated rather than a single value.
• Disjoint from next_milestone by construction: next_milestone is strictly above the reported balance, these are at or below it.

Regenerated the OpenAPI artifacts to match.

part of STORE-1488

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Note

Low Risk
Additive API documentation and proto field only; existing payloads stay unchanged when the field is omitted.

Overview
Purchase egress PlayerLoyaltyState now includes unlockedMilestones: milestones whose thresholds were crossed by that purchase’s points gain, each with milestoneId and rewards, reusing the existing Milestone shape. The field is additive (omitted when no threshold was crossed or points did not increase), can list multiple milestones in ascending order, and is documented as disjoint from nextMilestone.

The shared Milestone OpenAPI description is broadened from “next milestone only” to a generic milestone-and-rewards object. docs/gen/swagger.v1.json is regenerated for register/confirm payment and related schemas.

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[dinosoeren]

• feat(egress): report loyalty milestones unlocked by a purchase #35 👈 (View in Graphite)
• main

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