feat: v0.3.0-alpha — DNS management, email accounts, suspend/terminate, password change

Backend:
- routes/dns.rs: GET/POST/DELETE /api/dns/:domain (pdnsutil CRUD, SOA hidden, auto-rectify)
- routes/email.rs: GET/POST/DELETE email accounts with Maildir provisioning
- routes/me.rs: POST /api/me/password (verify current, hash new, update users+accounts)
- routes/accounts.rs: GET /api/accounts/:username, suspend, unsuspend, terminate (deprovision+userdel)
- main.rs: register all new routes; import axum::routing::delete
- Cargo.toml: version bump 0.2.0-alpha -> 0.3.0-alpha

NixServer:
- Zone Manager page: lists all PowerDNS zones, click -> DNS editor
- DNS Records page: add/delete records, colour-coded type badges, zone switcher
- Service Manager page: dedicated page with refresh + running/stopped pills
- List Accounts: Suspend/Unsuspend/Terminate buttons with confirmation modal
- Domain cell links to live site

NixClient:
- Domains page: primary domain info, document root, quota, bandwidth
- Email Accounts page: create/list/delete mailboxes with quota display
- Change Password page: Argon2id verify + update server-side
- AccountSidebar: fetches real account data (domain, package, quota)
- api.ts: listMyEmailAccounts, createEmailAccount, deleteEmailAccount, changePassword, getMyAccount(username)

CHANGELOG.md: v0.3.0-alpha entry

nixpanel-api/src/routes/mod.rs

@@ -1,4 +1,7 @@
 pub mod auth;
 pub mod accounts;
 pub mod dashboard;
+pub mod dns;
+pub mod email;
+pub mod me;
 pub mod services;