feat(workflows): migrate legacy workflows and enhance example handling

- Migrated legacy workflow files from `packages/server/workflows/` to `packages/server/data/workflows/` when the new store is empty.
- Introduced new API endpoints to list and retrieve example workflows.
- Added a dialog component for selecting example workflows when creating new workflows.
- Updated workflow paths and configurations to reflect the new structure.
- Enhanced the README and AGENTS.md documentation to clarify workflow management and usage.

Co-authored-by: Nasyarobby Putra <nasyarobby@gmail.com>

packages/server/package.json

@@ -13,7 +13,7 @@
     "start:control": "node control.js",
     "migrate": "node -e \"import('./db.js').then((m) => m.migrate().then(() => process.exit(0)))\"",
     "test:plugins": "JFLOW_PLUGINS_DIR=./data/plugins-smoke-test JFLOW_DB_PATH=./data/plugins-smoke.db node test/plugins-smoke.js",
-    "test:workflow-history": "node test/workflow-history-smoke.js",
+    "test:workflow-history": "JFLOW_WORKFLOWS_DIR=./data/workflow-history-smoke JFLOW_DB_PATH=./data/workflow-history-smoke.db node test/workflow-history-smoke.js",
     "test:profiles": "node test/profiles-smoke.js",
     "test:set-dry-run": "node test/set-dry-run-smoke.js"
   },