Initial npmctl: NPM CLI + generic API client

Rust CLI for Nginx Proxy Manager via its API, with sudo-like token auth
(login prompts for password, caches only a short-lived token, never the
password) and a generic `api` command to talk to any HTTP API.

Commands: login/logout/status, list-hosts/get-host/find, add-proxy,
enable/disable/delete-host, list-certs/add-cert/renew-cert, dump (JSON
backup), apply (declarative), and generic api (method/url/header/data/
auth-key/insecure).

Includes clap help + help-on-bad-input, Gitea Actions release workflow
(arm64 native + x64 cross), VS Code build task (-> ./build), README and
MIT license.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011YPrEZVBpPVoCRyJz2exkZ

.gitignore

@@ -0,0 +1,9 @@
+# Rust build output
+/target
+
+# Lokal build-mapp (VS Code-tasken lägger binären här) — ska inte in i repot
+/build
+
+# Diverse
+*.log
+.DS_Store