feat(FN-2992): merge fusion/fn-2992

Commits merged:
- fix(FN-2992): align ResearchView styles with design tokens
- fix(FN-2992): align Research view with standalone layout conventions
- test(FN-2992): complete Step 6 — expand orchestration verification
- feat(FN-2992): complete Step 5 — wire research settings and engine exports
- test(FN-2992): cover provider error classification in step runner
- feat(FN-2992): complete Step 4 — implement research step runner
- test(FN-2992): add orchestrator lifecycle regression coverage
- feat(FN-2992): complete Step 3 — add research orchestrator lifecycle
- feat(FN-2992): complete Step 2 — align research store API events
- feat(FN-2992): complete Step 1 — define orchestration domain types
- feat(FN-2992): complete Step 1 — define orchestration domain types

Files changed:
packages/core/src/index.ts                         |  15 +
 packages/core/src/research-store.ts                |   8 +-
 packages/core/src/research-types.ts                | 109 +++++
 packages/core/src/settings-schema.ts               |  10 +
 packages/core/src/types.ts                         |  31 ++
 packages/dashboard/app/components/ResearchView.css |  87 +++-
 packages/dashboard/app/components/ResearchView.tsx | 144 +++---
 .../app/components/__tests__/ResearchView.test.tsx |   3 +-
 .../src/__tests__/research-orchestrator.test.ts    | 256 ++++++++++
 .../src/__tests__/research-step-runner.test.ts     | 102 ++++
 packages/engine/src/index.ts                       |  11 +
 packages/engine/src/project-engine.ts              |  17 +
 packages/engine/src/research-orchestrator.ts       | 517 +++++++++++++++++++++
 packages/engine/src/research-step-runner.ts        | 235 ++++++++++
 14 files changed, 1464 insertions(+), 81 deletions(-)

Fusion-Task-Id: FN-2992

packages/engine/src/index.ts

@@ -53,6 +53,17 @@ export { WorktreePool, scanIdleWorktrees, cleanupOrphanedWorktrees, reapOrphanWo
 export { createLogger, type Logger } from "./logger.js";
 export { isUsageLimitError, UsageLimitPauser } from "./usage-limit-detector.js";
 export { withRateLimitRetry } from "./rate-limit-retry.js";
+export { ResearchOrchestrator, type ResearchOrchestratorOptions, type ResearchOrchestratorStatus, type ResearchOrchestratorStartOptions } from "./research-orchestrator.js";
+export {
+  ResearchStepRunner,
+  ResearchStepTimeoutError,
+  ResearchStepAbortError,
+  ResearchStepProviderError,
+  type ResearchProvider,
+  type ResearchStepRunnerApi,
+  type ResearchStepRunnerOptions,
+  type ResearchStepResult,
+} from "./research-step-runner.js";
 export { PrMonitor, type PrComment, type TrackedPr, type OnNewCommentsCallback } from "./pr-monitor.js";
 export { PrCommentHandler } from "./pr-comment-handler.js";
 export {