feat(migration): implement workspace layout migration and testing

- Added `migrate-layout.ts` to handle migration from old workspace layouts to the new `devclaw/` structure.
- Introduced `migrate-layout.test.ts` for comprehensive tests covering various migration scenarios.
- Updated `workspace.ts` to ensure default files are created post-migration, including `workflow.yaml` and role-specific prompts.
- Refactored role instruction handling to accommodate new directory structure.
- Enhanced project registration to scaffold prompt files in the new `devclaw/projects/<project>/prompts/` directory.
- Adjusted setup tool descriptions and logic to reflect changes in file structure.
- Updated templates to align with the new workflow configuration and role instructions.

lib/config/types.ts

@@ -1,13 +1,13 @@
 /**
  * config/types.ts — Types for the unified DevClaw configuration.
  *
- * A single config.yaml combines roles, models, and workflow.
+ * A single workflow.yaml combines roles, models, and workflow.
  * Three-layer resolution: built-in → workspace → per-project.
  */
 import type { WorkflowConfig } from "../workflow.js";
 
 /**
- * Role override in config.yaml. All fields optional — only override what you need.
+ * Role override in workflow.yaml. All fields optional — only override what you need.
  * Set to `false` to disable a role entirely for a project.
  */
 export type RoleOverride = {
@@ -19,7 +19,7 @@ export type RoleOverride = {
 };
 
 /**
- * The full config.yaml shape.
+ * The full workflow.yaml shape.
  * All fields optional — missing fields inherit from the layer below.
  */
 export type DevClawConfig = {