Add HTTP/HTTPS proxy support via undici ProxyAgent

[Copilot]

Node's built-in fetch (used by the generated API client) doesn't automatically honor HTTP_PROXY/HTTPS_PROXY/NO_PROXY, so the CLI was unable to reach app.codacy.com (or a custom CODACY_API_BASE_URL) from behind a corporate proxy on any Node version this CLI supports.

Proxy resolution helper

• New src/utils/proxy.ts:
  • resolveProxyUrl(env) — resolves HTTPS_PROXY/HTTP_PROXY (case-insensitive; uppercase and HTTPS_PROXY take priority).
  • shouldBypassProxy(env, host) — honors NO_PROXY/no_proxy (exact match, .suffix match, *) against the Codacy API host.
  • configureProxyFromEnv(env) — installs an undici.ProxyAgent via setGlobalDispatcher when applicable; returns undefined (no-op) when no proxy is configured or it's bypassed.

Wiring

• src/index.ts calls configureProxyFromEnv() before OpenAPI.BASE/OpenAPI.HEADERS are set and before any command is registered, so every subsequent fetch() routes through the proxy automatically.
• Added undici as a direct dependency rather than relying on the transitive copy or Node 24's experimental NODE_USE_ENV_PROXY.

Docs & changeset

• README.md: new "Proxy Support" section.
• AGENTS.md: HTTPS_PROXY/HTTP_PROXY/NO_PROXY added to the Environment Variables table.
• Minor changeset added.

HTTPS_PROXY=http://proxyhost:port codacy info