story-kit: merge 166_story_add_done_column_to_pipeline_board

Add Done column to pipeline board. Adds the 'done' stage to
PipelineState, exposes it via the WebSocket and REST API, and
renders a Done column in the frontend pipeline board view.

Squash merge from feature/story-166_story_add_done_column_to_pipeline_board.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/Chat.tsx

@@ -72,6 +72,7 @@ export function Chat({ projectPath, onCloseProject }: ChatProps) {
 		current: [],
 		qa: [],
 		merge: [],
+		done: [],
 	});
 	const [claudeSessionId, setClaudeSessionId] = useState<string | null>(null);
 	const [activityStatus, setActivityStatus] = useState<string | null>(null);
@@ -1074,6 +1075,7 @@ export function Chat({ projectPath, onCloseProject }: ChatProps) {
 							stateVersion={agentStateVersion}
 						/>
 
+						<StagePanel title="Done" items={pipeline.done} />
 						<StagePanel title="To Merge" items={pipeline.merge} />
 						<StagePanel title="QA" items={pipeline.qa} />
 						<StagePanel title="Current" items={pipeline.current} />

frontend/src/components/LozengeFlyContext.test.tsx

@@ -13,6 +13,7 @@ function makePipeline(overrides: Partial<PipelineState> = {}): PipelineState {
 		current: [],
 		qa: [],
 		merge: [],
+		done: [],
 		...overrides,
 	};
 }