Build domain-blank figured-out NodeKit foundation

[HomenShum]

What changed

• makes nodekit create generate one blank-in-domain, figured-out-in-behavior application
• removes every public preset, domain chooser, reference generator, and silent fallback
• excludes repository-internal narrow examples from the npm package
• adds portable Caseflow lifecycle semantics, a memory runtime, and provider conformance
• ships the artifact-first responsive UI and deterministic no-key proof path
• separates engineering review, developer alpha, ease certification, Convex maturity, submission, and portability in docs/RELEASE_LADDER.md
• reports small timing samples honestly; p95 is withheld until a cell has at least 20 observations

Why

NodeKit should not choose a domain for the builder. It should make the difficult product behavior already figured out, then let a coding agent research and specialize the blank foundation from the user's real job.

The release ladder also prevents later validation goals from blocking or overstating earlier engineering decisions.

Current status

• E0 engineering foundation: ready for independent PR review
• E1 developer alpha: incomplete; fresh-agent canary and revision-bound preview remain required
• E2/E3 ease claims: incomplete and fail-closed
• C1 Convex adapter: not yet proven
• C2 component extraction: blocked on three materially different consumers
• C3 Convex submission: blocked; no submission, publication, or release is authorized
• P1 portability: future work

Validation

• npm test: 68/68 passing
• Windows, Ubuntu, and macOS CI factory lanes previously passed for npm and pnpm
• npm pack --dry-run: reference-apps absent
• CLI help contains no preset or reference-create path
• canonical UI proof: 180 screenshots across 15 states and six viewport/theme profiles, with trace and video
• NodeProof independently verifies the committed screenshot, trace, and video evidence
• no unresolved serious/critical axe findings, console errors, failed requests, overflow, or mojibake in the canonical UI packet

Deliberate limits

This PR does not claim that unfamiliar developers or coding agents already find NodeKit super easy. It does not prove a production Convex adapter, three consumers, a public component, backend portability, npm publication, or Convex directory readiness. Those remain separate gates.