Add player outfit management RPCs with user-scoped storage

[Copilot]

Implements CRUD operations for player cosmetic outfits stored in Nakama storage.

Endpoints

Four RPCs registered in evr_runtime.go:

• player/outfit/save - Creates outfit with generated UUID, enforces 10-outfit limit per user
• player/outfit/list - Returns all outfits for authenticated user
• player/outfit/load - Retrieves specific outfit by ID
• player/outfit/delete - Deletes after ownership verification

Storage Schema

Collection: player_outfits (user-scoped)

type Outfit struct {
    ID      string      `json:"id"`       // UUID v4
    Name    string      `json:"name"`
    Chassis string      `json:"chassis"`
    Bracer  string      `json:"bracer"`
    Booster string      `json:"booster"`
    Decal   string      `json:"decal"`
    SavedAt TimeRFC3339 `json:"saved_at"`
}

Implementation Notes

• Authentication required on all endpoints (extracts user ID from context)
• Storage operations scoped to authenticated user ID - prevents cross-user access
• Delete verifies outfit exists and belongs to user before removal
• MaxOutfitsPerUser constant (10) configurable for environment-specific limits

Example Usage

POST /v2/rpc/player/outfit/save
{
  "name": "Competition Loadout",
  "chassis": "chassis_001",
  "bracer": "bracer_002",
  "booster": "booster_003",
  "decal": "decal_004"
}

Response: {
  "success": true,
  "outfit": { /* full outfit object */ },
  "id": "550e8400-e29b-41d4-a716-446655440000"
}

Original prompt

Implement outfit management RPCs in server/evr_runtime_rpc.go

Storage: Use Nakama storage with collection "player_outfits", user-scoped.

Outfit schema:

• id: uuid
• name: string
• chassis, bracer, booster, decal: string IDs
• saved_at: timestamp

Endpoints:

1. player/outfit/save
   Request: {name, chassis, bracer, booster, decal}
   Response: {success, outfit, id}

   • Generate UUID for new outfits
   • Limit to 10 outfits per user (configurable)

2. player/outfit/list
   Request: (none)
   Response: {outfits: [...]}

3. player/outfit/load
   Request: {outfit_id}
   Response: {success, outfit}

4. player/outfit/delete
   Request: {outfit_id}
   Response: {success}

   • Verify ownership before delete

Register all RPCs in runtime initialization.

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