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

.vscode/tasks.json

@@ -0,0 +1,31 @@
+{
+  "version": "2.0.0",
+  "tasks": [
+    {
+      "label": "build (release -> ./build)",
+      "detail": "Bygger npmctl i release-läge och lägger binären i ./build/npmctl",
+      "type": "shell",
+      "options": {
+        "shell": { "executable": "/bin/bash", "args": ["-c"] },
+        "env": {
+          "//": "Bygg utanför NTFS-disken (cargo skapar många småfiler); kopiera sedan bara binären in i repot.",
+          "CARGO_TARGET_DIR": "${env:HOME}/.cache/npmctl-target"
+        }
+      },
+      "command": "cargo build --release && mkdir -p build && cp \"$CARGO_TARGET_DIR/release/npmctl\" build/npmctl && echo '--> build/npmctl' && ls -la build/",
+      "problemMatcher": ["$rustc"],
+      "group": { "kind": "build", "isDefault": true }
+    },
+    {
+      "label": "run -- status",
+      "detail": "Bygger och kör `npmctl status`",
+      "type": "shell",
+      "options": {
+        "shell": { "executable": "/bin/bash", "args": ["-c"] },
+        "env": { "CARGO_TARGET_DIR": "${env:HOME}/.cache/npmctl-target" }
+      },
+      "command": "cargo run --release -- status",
+      "problemMatcher": ["$rustc"]
+    }
+  ]
+}