feat: sync upstream spec

[64bit]

New Types (Responses module)

• MessagePhase enum: Commentary, FinalAnswer - labels assistant messages as intermediate
  commentary or final answer
• ToolSearchExecutionType enum: Server, Client
• SearchContentType enum: Text, Image - for web search content type filtering
• FunctionCallStatus enum: InProgress, Completed, Incomplete
• FunctionCallOutputStatusEnum enum: InProgress, Completed, Incomplete
• ComputerTool struct: simple tool type for computer (no config fields)
• NamespaceToolParam struct: groups function/custom tools under a shared namespace
• FunctionToolParam struct: function tool used within namespaces/tool search
• NamespaceToolParamTool enum: Function/Custom discriminated union
• ToolSearchToolParam struct: hosted or BYOT tool search config
• ToolSearchCall / ToolSearchCallItemParam: tool search call items (output/input)
• ToolSearchOutput / ToolSearchOutputItemParam: tool search output items (output/input)

Updated Enums

• ImageDetail (shared): added Original variant
• Tool: added Computer, Namespace, ToolSearch variants
• ToolChoiceTypes: added Computer, ComputerUse, WebSearchPreview20250311 variants
• OutputItem: added ToolSearchCall, ToolSearchOutput variants
• Item: added ToolSearchCall, ToolSearchOutput variants
• ItemResourceItem: added ToolSearchCall, ToolSearchOutput variants
• ConversationItem: added ToolSearchCall, ToolSearchOutput, ShellCall, ShellCallOutput,
  ApplyPatchCall, ApplyPatchCallOutput variants

Updated Structs

• EasyInputMessage: added phase: Option
• OutputMessage: added phase: Option
• ComputerToolCall: added actions: Option<Vec>, made action Option
• FunctionToolCall: added namespace: Option
• CustomToolCall: added namespace: Option
• FunctionTool: added defer_loading: Option
• CustomToolParam: added defer_loading: Option
• MCPTool: added defer_loading: Option
• WebSearchTool: added search_content_types: Option<Vec>
• CompactResponseRequest: added prompt_cache_key: Option

Video Module

• VideoCharacterResource: new struct for character creation/retrieval
• VideoReferenceInput: new struct for referencing completed videos
• ImageRefParam: new struct for image reference parameters
• VideoSeconds: updated enum with 4, 8, 12, 16, 20 values
• VideoEditInput: new enum for edit/extend input (reference or file)
• CreateVideoCharacterRequest: new request type
• CreateVideoEditRequest: new request type
• CreateVideoExtendRequest: new request type
• New API endpoints: create_character(), get_character(), edit(), extend()

Audio Module

• Voice enum: added Marin, Cedar variants and Custom(CustomVoiceRef) variant for custom
  voice references
• CustomVoiceRef struct: custom voice reference with id field