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/package.json

@@ -9,19 +9,18 @@
   "type": "module",
   "exports": {
     ".": {
-      "bun": "./src/index.ts",
       "types": "./dist/index.d.ts",
       "import": "./dist/index.js"
     }
   },
   "scripts": {
-    "prepublishOnly": "echo 'Use bun run release from repo root' && exit 1",
-    "test": "bun test __tests__/ src/__tests__/",
-    "test:ci": "bun test __tests__/ src/__tests__/"
+    "prepublishOnly": "echo 'Use pnpm run release from repo root' && exit 1",
+    "test": "vitest run __tests__/ src/__tests__/",
+    "test:ci": "vitest run __tests__/ src/__tests__/"
   },
   "dependencies": {
-    "@ocas/core": "^0.1.1",
-    "@ocas/fs": "^0.1.1",
+    "@ocas/core": "^0.2.2",
+    "@ocas/fs": "^0.2.2",
     "@united-workforce/protocol": "workspace:^",
     "@united-workforce/util": "workspace:^",
     "dotenv": "^16.6.1",