feat: Implement Architect role & design_task tool (#189)

Adds the Architect role for design/architecture investigations with
persistent sessions and structured design proposals.

## New Features

- **Architect role** with opus (complex) and sonnet (standard) levels
- **design_task tool** — Creates To Design issues and dispatches architect
- **Workflow states:** To Design → Designing → Planning
- **Completion rules:** architect:done → Planning, architect:blocked → Refining
- **Auto-level selection** based on complexity keywords

## Files Changed (22 files, 546 additions)

### New Files
- lib/tools/design-task.ts — design_task tool implementation
- lib/tools/design-task.test.ts — 16 tests for architect functionality

### Core Changes
- lib/tiers.ts — ARCHITECT_LEVELS, WorkerRole type, models, emoji
- lib/workflow.ts — toDesign/designing states, completion rules
- lib/projects.ts — architect WorkerState on Project type
- lib/dispatch.ts — architect role support in dispatch pipeline
- lib/services/pipeline.ts — architect completion rules
- lib/model-selector.ts — architect level selection heuristic

### Integration
- index.ts — Register design_task tool, architect config schema
- lib/notify.ts — architect role in notifications
- lib/bootstrap-hook.ts — architect session key parsing
- lib/services/tick.ts — architect in queue processing
- lib/services/heartbeat.ts — architect in health checks
- lib/tools/health.ts — architect in health scans
- lib/tools/status.ts — architect in status dashboard
- lib/tools/work-start.ts — architect role option
- lib/tools/work-finish.ts — architect validation
- lib/tools/project-register.ts — architect labels + role scaffolding
- lib/templates.ts — architect instructions + AGENTS.md updates
- lib/setup/workspace.ts — architect role file scaffolding
- lib/setup/smart-model-selector.ts — architect in model assignment
- lib/setup/llm-model-selector.ts — architect in LLM prompt

lib/tools/work-finish.ts

@@ -21,7 +21,7 @@ export function createWorkFinishTool(api: OpenClawPluginApi) {
       type: "object",
       required: ["role", "result", "projectGroupId"],
       properties: {
-        role: { type: "string", enum: ["dev", "qa"], description: "Worker role" },
+        role: { type: "string", enum: ["dev", "qa", "architect"], description: "Worker role" },
         result: { type: "string", enum: ["done", "pass", "fail", "refine", "blocked"], description: "Completion result" },
         projectGroupId: { type: "string", description: "Project group ID" },
         summary: { type: "string", description: "Brief summary" },
@@ -30,7 +30,7 @@ export function createWorkFinishTool(api: OpenClawPluginApi) {
     },
 
     async execute(_id: string, params: Record<string, unknown>) {
-      const role = params.role as "dev" | "qa";
+      const role = params.role as "dev" | "qa" | "architect";
       const result = params.result as string;
       const groupId = params.projectGroupId as string;
       const summary = params.summary as string | undefined;
@@ -40,6 +40,8 @@ export function createWorkFinishTool(api: OpenClawPluginApi) {
       // Validate role:result
       if (role === "dev" && result !== "done" && result !== "blocked")
         throw new Error(`DEV can only complete with "done" or "blocked", got "${result}"`);
+      if (role === "architect" && result !== "done" && result !== "blocked")
+        throw new Error(`ARCHITECT can only complete with "done" or "blocked", got "${result}"`);
       if (role === "qa" && result === "done")
         throw new Error(`QA cannot use "done". Use "pass", "fail", "refine", or "blocked".`);
       if (!getRule(role, result))