refactor: Centralize role types and configuration (#190)

Creates a single source of truth for all worker roles via lib/roles/.

## New: lib/roles/

- **registry.ts** — All role definitions (dev, qa, architect) with
  levels, models, emoji, completion results, session key patterns
- **types.ts** — RoleConfig interface
- **selectors.ts** — Query helpers: getRole(), getLevelsForRole(),
  resolveModel(), isValidResult(), roleForLevel(), etc.
- **index.ts** — Barrel exports

## Migrated Files

- **lib/tiers.ts** — Now delegates to registry (backward compat kept)
- **lib/dispatch.ts** — Uses registry for emoji resolution
- **lib/bootstrap-hook.ts** — Uses registry for session key pattern
- **lib/services/tick.ts** — Uses registry for level detection
- **lib/services/heartbeat.ts** — Uses registry for role iteration
- **lib/tools/health.ts** — Uses registry for role iteration
- **lib/tools/work-start.ts** — Uses registry for role enum
- **lib/tools/work-finish.ts** — Uses registry for result validation
- **lib/tools/project-register.ts** — Uses registry for level lists

## Key Benefits

- Adding a new role = add entry to registry.ts (single file)
- No more scattered role unions ("dev" | "qa" | "architect")
- Type-safe role/level/result validation from registry
- Session key pattern auto-generated from registry
- All 64 tests passing (22 new registry tests + 42 existing)

lib/tools/work-start.ts

@@ -14,6 +14,7 @@ import { getWorker } from "../projects.js";
 import { dispatchTask } from "../dispatch.js";
 import { findNextIssue, detectRoleFromLabel, detectLevelFromLabels } from "../services/tick.js";
 import { isDevLevel } from "../tiers.js";
+import { getAllRoleIds } from "../roles/index.js";
 import { requireWorkspaceDir, resolveProject, resolveProvider, getPluginConfig } from "../tool-helpers.js";
 import { DEFAULT_WORKFLOW, getActiveLabel } from "../workflow.js";
 
@@ -28,7 +29,7 @@ export function createWorkStartTool(api: OpenClawPluginApi) {
       properties: {
         projectGroupId: { type: "string", description: "Project group ID." },
         issueId: { type: "number", description: "Issue ID. If omitted, picks next by priority." },
-        role: { type: "string", enum: ["dev", "qa", "architect"], description: "Worker role. Auto-detected from label if omitted." },
+        role: { type: "string", enum: getAllRoleIds(), description: "Worker role. Auto-detected from label if omitted." },
         level: { type: "string", description: "Developer level (junior/medior/senior/reviewer). Auto-detected if omitted." },
       },
     },