chore: migrate from bun to pnpm + vitest + esbuild

- Replace bun:test with vitest across all packages
- Replace bun build with esbuild
- Replace bun:sqlite with better-sqlite3
- Fix OCAS Store API: store.put/get → store.cas.put/get
- Fix vitest vi.mock hoisting (vi.hoisted)
- Add pnpm-workspace.yaml and pnpm-lock.yaml
- Update all package.json test/build scripts

WIP: 8 failures remain in agent-hermes (bun engines check + sqlite migration)

Refs #26

packages/dashboard/src/editor/layout/__tests__/layout.test.ts

@@ -1,4 +1,4 @@
-import { describe, expect, it } from "bun:test";
+import { describe, expect, it } from 'vitest';
 import type { Edge, Node } from "@xyflow/react";
 import { LayoutLR } from "../index.js";
 

packages/dashboard/src/editor/trans/__tests__/trans-in.test.ts

@@ -1,4 +1,4 @@
-import { describe, expect, it } from "bun:test";
+import { describe, expect, it } from 'vitest';
 import { transIn } from "../trans-in.js";
 import type { WorkFlowStep } from "../type.js";
 

packages/dashboard/src/editor/trans/__tests__/validate.test.ts

@@ -1,4 +1,4 @@
-import { describe, expect, it } from "bun:test";
+import { describe, expect, it } from 'vitest';
 import type { AnyWorkEdge, AnyWorkNode } from "../../type.js";
 import { validate } from "../validate.js";