Rename standalone 'phase' artifacts to readiness/functional names

[jooh]

Motivation

• Remove legacy "phase" framing used during the port and organize migration scaffolding by functional readiness areas.
• Make evaluator, test, Rust module, and docs names describe intent (prototype, distribution, native foundation, cutover) instead of implementation phases.
• Ensure tooling and guardrails (setup-separation check, scripts, TODOs) reflect the new naming and remain deterministic.

Description

• Renamed TypeScript migration evaluators and types from standalonePhase*/Phase* to descriptive readiness names and signatures (for example standalonePhase1.ts → prototypeReadiness.ts, evaluatePhase1 → evaluatePrototypeReadiness, REQUIRED_PHASE1_COMMANDS → REQUIRED_PROTOTYPE_COMMANDS).
• Renamed tests to match evaluators (for example src/test/standalonePhase1.test.ts → src/test/prototypeReadiness.test.ts) and updated imports/expectations to use the new readiness strings.
• Renamed Rust modules and APIs: phase4.rs → command_porting.rs and phase5.rs → cutover.rs, updated public constants/struct/enum/function names (for example evaluate_phase4 → evaluate_command_porting, REQUIRED_PHASE4_EXECUTION_COMMANDS → REQUIRED_EXECUTION_COMMANDS) and adjusted main.rs module wiring and top-level command constant (PHASE3_COMMANDS → SUPPORTED_TOP_LEVEL_COMMANDS).
• Updated documentation and reports under docs/standalone/ to descriptive names (phase1.md/phase2.md/phase3.md/phase5.md → prototype.md/distribution.md/native-foundation.md/cutover.md) and revised TODO headings/phrasing to an implementation workstreams model.
• Adjusted guardrail tooling and helper scripts to the new naming pattern (build/check-setup-separation.js now matches /(?:.*Readiness)\.ts$/ and error messages reference readiness evaluators; scripts/standalone/build-linux-x64.sh wording updated).

Testing

• Ran npm run check-setup-separation and it passed.
• Ran the TypeScript unit tests for the readiness evaluators with env TS_NODE_PROJECT=src/test/tsconfig.json npx mocha -r ts-node/register --exit src/test/prototypeReadiness.test.ts src/test/distributionReadiness.test.ts src/test/nativeFoundationReadiness.test.ts src/test/cutoverReadiness.test.ts and all tests passed (9 passing).
• Ran Rust tests with cargo test in cmd/devcontainer-native and they passed (11 passed).

---

Codex Task