feat: export FormatId, PackageRequest, PushNotificationConfig, and PriceGuidance from stable API (#68)

Add missing types to stable.py public API:
- FormatId: Format identifier type (agent_url + id)
- PackageRequest: Request structure for creating packages
- PushNotificationConfig: Webhook push notification configuration
- PriceGuidance: Pricing guidance for auction-based options (floor, percentiles)

These types are commonly used in AdCP workflows and should be part of
the stable public API to avoid users importing from internal generated modules.

Changes:
- Add types to adcp.types.stable imports and __all__
- Add types to adcp.__init__.py imports and __all__
- Group PriceGuidance with other pricing types
- Add new "Configuration types" section for PushNotificationConfig

All types are properly exported from both stable.py and main package.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude <noreply@anthropic.com>

Author: bokelley

src/adcp/__init__.py

@@ -132,6 +132,7 @@
     Error,
     FlatRatePricingOption,
     Format,
+    FormatId,
     GetMediaBuyDeliveryRequest,
     GetMediaBuyDeliveryResponse,
     GetProductsRequest,
@@ -147,14 +148,17 @@
     MediaBuy,
     MediaBuyStatus,
     Package,
+    PackageRequest,
     PackageStatus,
     PreviewCreativeRequest,
     PreviewCreativeResponse,
+    PriceGuidance,
     PricingModel,
     Product,
     Property,
     ProvidePerformanceFeedbackRequest,
     ProvidePerformanceFeedbackResponse,
+    PushNotificationConfig,
     SyncCreativesRequest,
     SyncCreativesResponse,
     UpdateMediaBuyRequest,
@@ -214,6 +218,7 @@
     "ProvidePerformanceFeedbackResponse",
     "Error",
     "Format",
+    "FormatId",
     "Product",
     "Property",
     # Core domain types (from stable API)
@@ -222,23 +227,27 @@
     "CreativeManifest",
     "MediaBuy",
     "Package",
+    "PackageRequest",
     # Package type aliases
     "CreatedPackageReference",
     # Status enums (for control flow)
     "CreativeStatus",
     "MediaBuyStatus",
     "PackageStatus",
     "PricingModel",
-    # Pricing options (all 9 types)
+    # Pricing-related types
     "CpcPricingOption",
     "CpcvPricingOption",
     "CpmAuctionPricingOption",
     "CpmFixedRatePricingOption",
     "CppPricingOption",
     "CpvPricingOption",
     "FlatRatePricingOption",
+    "PriceGuidance",
     "VcpmAuctionPricingOption",
     "VcpmFixedRatePricingOption",
+    # Configuration types
+    "PushNotificationConfig",
     # Adagents validation
     "AuthorizationContext",
     "fetch_adagents",

src/adcp/types/stable.py

@@ -48,6 +48,7 @@
     Error,
     FlatRatePricingOption,
     Format,
+    FormatId,
     GetMediaBuyDeliveryRequest,
     GetMediaBuyDeliveryResponse,
     GetProductsRequest,
@@ -66,14 +67,17 @@
     MarkdownAsset,
     MediaBuy,
     MediaBuyStatus,
+    PackageRequest,
     PackageStatus,
     PreviewCreativeRequest,
     PreviewCreativeResponse,
+    PriceGuidance,
     PricingModel,
     Product,
     Property,
     ProvidePerformanceFeedbackRequest,
     ProvidePerformanceFeedbackResponse,
+    PushNotificationConfig,
     SyncCreativesRequest,
     SyncCreativesResponse,
     TasksGetRequest,
@@ -143,18 +147,21 @@
     "CreativeManifest",
     "Error",
     "Format",
+    "FormatId",
     "MediaBuy",
     "Package",
+    "PackageRequest",
     "Product",
     "Property",
-    # Pricing options
+    # Pricing-related types
     "CpcPricingOption",
     "CpcvPricingOption",
     "CpmAuctionPricingOption",
     "CpmFixedRatePricingOption",
     "CppPricingOption",
     "CpvPricingOption",
     "FlatRatePricingOption",
+    "PriceGuidance",
     "VcpmAuctionPricingOption",
     "VcpmFixedRatePricingOption",
     # Status enums
@@ -164,6 +171,8 @@
     "PricingModel",
     "TaskStatus",
     "TaskType",
+    # Configuration types
+    "PushNotificationConfig",
     # Assets
     "AudioAsset",
     "CssAsset",