Story 26: Establish TDD workflow and quality gates

Add workflow engine with acceptance gates, test recording, and review
queue. Frontend displays gate status (blocked/ready), test summaries,
failing badges, and warnings. Proceed action is disabled when gates
are not met. Includes 13 unit tests (Vitest) and 9 E2E tests
(Playwright) covering all five acceptance criteria.

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

server/src/http/mod.rs

@@ -5,6 +5,7 @@ pub mod context;
 pub mod health;
 pub mod io;
 pub mod model;
+pub mod workflow;
 
 pub mod project;
 pub mod ws;
@@ -19,6 +20,7 @@ use poem::{Route, get};
 use poem_openapi::OpenApiService;
 use project::ProjectApi;
 use std::sync::Arc;
+use workflow::WorkflowApi;
 
 pub fn build_routes(ctx: AppContext) -> impl poem::Endpoint {
     let ctx_arc = std::sync::Arc::new(ctx);
@@ -36,7 +38,14 @@ pub fn build_routes(ctx: AppContext) -> impl poem::Endpoint {
         .data(ctx_arc)
 }
 
-type ApiTuple = (ProjectApi, ModelApi, AnthropicApi, IoApi, ChatApi);
+type ApiTuple = (
+    ProjectApi,
+    ModelApi,
+    AnthropicApi,
+    IoApi,
+    ChatApi,
+    WorkflowApi,
+);
 
 type ApiService = OpenApiService<ApiTuple, ()>;
 
@@ -48,6 +57,7 @@ pub fn build_openapi_service(ctx: Arc<AppContext>) -> (ApiService, ApiService) {
         AnthropicApi::new(ctx.clone()),
         IoApi { ctx: ctx.clone() },
         ChatApi { ctx: ctx.clone() },
+        WorkflowApi { ctx: ctx.clone() },
     );
 
     let api_service =
@@ -58,7 +68,8 @@ pub fn build_openapi_service(ctx: Arc<AppContext>) -> (ApiService, ApiService) {
         ModelApi { ctx: ctx.clone() },
         AnthropicApi::new(ctx.clone()),
         IoApi { ctx: ctx.clone() },
-        ChatApi { ctx },
+        ChatApi { ctx: ctx.clone() },
+        WorkflowApi { ctx },
     );
 
     let docs_service =