feat(officialmcp): reconnecting session via ClientSession anti-corruption interface (#889)

• feat(components): upgrade officialmcp with tool name mapping, session management, and result policies

Add ToolNameMapper, MetadataMode, ListToolsMode, ResultPolicy, DescriptionPolicy, and ToolCallResultHandler/V2 to officialmcp Config. Introduce session sub-package for streamable HTTP and stdio transport lifecycle management.

Change-Id: Ie23aee61a185672106680f73998a4093d7bfb40f

• fix(adk): respect explicit execute mode precedence

Change-Id: I46254284516e09606572fb5da57f108446270db7

• feat(adk): route auto/background+wait streaming through rich path

ExecuteStreaming now bridges to executeRich via a single-frame stream when Mode=auto or Mode=background with WaitMS>0, ensuring symmetric exit-code propagation and timer-based backgrounding semantics with the non-streaming Execute path. Adds attack regression tests covering default wait, non-zero exit, context cancellation, timer backgrounding, background+wait completion, and early receiver close.

Change-Id: Idbca60aae9827e4139f618bd54d779202a67a7ea

• feat(officialmcp): reconnecting session via ClientSession anti-corruption interface

Bump go-sdk to v1.6.1 and make Config.Cli a ClientSession interface (ListTools/CallTool/Ping/Close) that *mcp.ClientSession satisfies directly. Classify connection-level failures (ErrConnectionClosed/ErrSessionMissing) as ErrorKindConnection, distinct from protocol-level rejections, so bad-args tool calls cannot cause reconnect churn. The session package’s Session implements the interface and transparently rebuilds the underlying go-sdk session on connection-level errors (single reconnect under concurrent failures).