Add goal app-server API (2 / 5) (#18074)

Adds the app-server v2 goal API on top of the persisted goal state from
PR 1.

## Why

Clients need a stable app-server surface for reading and controlling
materialized thread goals before the model tools and TUI can use them.
Goal changes also need to be observable by app-server clients, including
clients that resume an existing thread.

## What changed

- Added v2 `thread/goal/get`, `thread/goal/set`, and `thread/goal/clear`
RPCs for materialized threads.
- Added `thread/goal/updated` and `thread/goal/cleared` notifications so
clients can keep local goal state in sync.
- Added resume/snapshot wiring so reconnecting clients see the current
goal state for a thread.
- Added app-server handlers that reconcile persisted rollout state
before direct goal mutations.
- Updated the app-server README plus generated JSON and TypeScript
schema fixtures for the new API surface.

## Verification

- Added app-server v2 coverage for goal get/set/clear behavior,
notification emission, resume snapshots, and non-local thread-store
interactions.

codex-rs/rollout-trace/src/protocol_event.rs

@@ -226,6 +226,7 @@ pub(crate) fn tool_runtime_trace_event(event: &EventMsg) -> Option<ToolRuntimeTr
         | EventMsg::ModelVerification(_)
         | EventMsg::ContextCompacted(_)
         | EventMsg::ThreadRolledBack(_)
+        | EventMsg::ThreadGoalUpdated(_)
         | EventMsg::TurnStarted(_)
         | EventMsg::TurnComplete(_)
         | EventMsg::TokenCount(_)
@@ -317,6 +318,7 @@ pub(crate) fn wrapped_protocol_event_type(event: &EventMsg) -> Option<&'static s
         | EventMsg::AgentReasoningRawContent(_)
         | EventMsg::AgentReasoningRawContentDelta(_)
         | EventMsg::AgentReasoningSectionBreak(_)
+        | EventMsg::ThreadGoalUpdated(_)
         | EventMsg::McpStartupUpdate(_)
         | EventMsg::McpStartupComplete(_)
         | EventMsg::McpToolCallBegin(_)
@@ -403,8 +405,9 @@ impl TraceExecutionStatus for PatchApplyStatus {
 
 fn execution_status_for_abort_reason(reason: &TurnAbortReason) -> ExecutionStatus {
     match reason {
-        TurnAbortReason::Interrupted | TurnAbortReason::Replaced | TurnAbortReason::ReviewEnded => {
-            ExecutionStatus::Cancelled
-        }
+        TurnAbortReason::Interrupted
+        | TurnAbortReason::Replaced
+        | TurnAbortReason::ReviewEnded
+        | TurnAbortReason::BudgetLimited => ExecutionStatus::Cancelled,
     }
 }