feat: real account provisioner, fix NixClient auth bypass

- nixpanel-accounts: creates Apache vhost, PHP-FPM pool, PowerDNS
  zone (A/MX/SPF records), home dir structure, default index.html
- nixpanel-api: create_account now calls provisioner after DB insert
- NixClient: replace fake setTimeout login with real JWT API call;
  admin accounts blocked with redirect message; logout clears token
- CHANGELOG updated

nixpanel-accounts/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name    = "nixpanel-accounts"
+version = "0.2.0-alpha"
+edition = "2021"
+
+[[bin]]
+name = "nixpanel-accounts"
+path = "src/main.rs"
+
+[dependencies]
+nixpanel-common = { path = "../nixpanel-common" }
+serde            = { version = "1", features = ["derive"] }
+serde_json       = "1"