feat: PostHog product analytics (#58)

* wip: posthog analytics

* wip: remove posthog-rs crate; call endpoint directly

* make analytics non-blocking

* session start event

* configure analytics for release builds

* remove dev_server_stopped event

* address review comments

* simplify analytics enabled logic

* analytics on by default; send start_session when user enables analytics; new task_attempt_start event

* lower visibility of analytics logs

* chore: bump version to 0.0.37-0

* set analytics to true if previously unset

---------

Co-authored-by: GitHub Action <action@github.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "vibe-kanban",
-  "version": "0.0.37-clash.0",
+  "version": "0.0.37-0",
   "private": true,
   "scripts": {
     "dev": "export FRONTEND_PORT=$(node scripts/setup-dev-environment.js frontend) && export BACKEND_PORT=$(node scripts/setup-dev-environment.js backend) && concurrently \"cargo watch -w backend -x 'run --manifest-path backend/Cargo.toml'\" \"npm run frontend:dev\"",
@@ -26,4 +26,4 @@
     "node": ">=18",
     "pnpm": ">=8"
   }
-}
+}