Craft Cloudflare target: deployType defaults to worker, account ID optional

Cloudflare target's deployType config default flipped from pages to worker (Cloudflare is steering new projects to Workers; Pages is positioned as legacy but still supported via deployType: pages). CLOUDFLARE_ACCOUNT_ID is optional — only CLOUDFLARE_API_TOKEN is required/secret; account ID is a non-secret identifier, forwarded to wrangler only when set, else wrangler auto-discovers it (single-account tokens) or errors listing account IDs in non-interactive/CI multi-account cases. No Cloudflare SDK added — raw global fetch used (Node 24.18.0 baseline). CLOUDFLARE_API_TOKEN always passed via env vars, never CLI argv/logs. Wrangler v4 has no built-in OIDC/keyless auth (unlike craft's npm target OIDC path) — auth is via API token, legacy Global API Key (deprecated), or wrangler login OAuth only. Introduced as a PR #843 follow-up; adversarial review verdict: solid, no CRITICAL/MAJOR issues.