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>

plugins/get-current-time/jerapah-plugin.json

@@ -0,0 +1,8 @@
+{
+  "id": "get-current-time",
+  "name": "Get current time",
+  "version": "0.1.0",
+  "jerapah": ">=0.1.0 <1.0.0",
+  "main": "script.js",
+  "description": "Example user plugin: return the current time as output.datetime"
+}