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/util-agent/__tests__/adapter-retry.test.ts

@@ -1,5 +1,5 @@
-import { describe, expect, test } from "bun:test";
-import { createMemoryStore, putSchema } from "@ocas/core";
+import { describe, expect, test } from 'vitest';
+import { createMemoryStore, putSchema, bootstrap } from "@ocas/core";
 
 import { tryFrontmatterFastPath } from "../src/frontmatter.js";
 
@@ -18,6 +18,7 @@ const PLANNER_SCHEMA = {
 describe("adapter-stdout: A4 retry loop survives JSON output", () => {
   test("A4. first extraction fails, second succeeds — final result has correct data", async () => {
     const store = createMemoryStore();
+    bootstrap(store);
     const schemaHash = await putSchema(store, PLANNER_SCHEMA);
 
     // Simulate the retry loop from createAgent (run.ts lines 163-173):
@@ -56,6 +57,7 @@ describe("adapter-stdout: A4 retry loop survives JSON output", () => {
 
   test("A4. all retries fail — extraction returns null on every attempt", async () => {
     const store = createMemoryStore();
+    bootstrap(store);
     const schemaHash = await putSchema(store, PLANNER_SCHEMA);
 
     const MAX_RETRIES = 2;