Closes #95: engine: claude is selectable but cannot actually be used

[simplycubed-code]

Automated change from an issue. A human reviews and merges; this loop does not.

Walkthrough

This change makes engine: claude usable through the local CLI path that was already wired up underneath. preflight and prepare now load the repo config before validating engine settings, skip Azure credential checks when the selected engine is Claude, and avoid rendering Codex provider config for a Claude run. That removes the false Azure dependency from local Claude executions while preserving the existing Azure-backed Codex path.

The documentation is updated to match the new boundary precisely. README, setup docs, and status notes now say that Claude works for local CLI runs authenticated through the claude CLI, but the reusable GitHub Actions workflow is still Codex-on-Azure only because it installs only the Codex CLI and still requires Azure inputs and secrets.

Changes

Area	Summary
CLI engine setup	Config-aware engine validation now skips Azure requirements and Codex config generation for local engine: claude runs.
Test coverage	CLI tests now cover Claude preflight and prepare flows without Azure variables, plus the absence of generated Codex config.
User-facing docs	README, status notes, and setup guidance now describe Claude as local-CLI-only and keep GitHub Actions documented as Azure/Codex-only.

Sequence diagram

sequenceDiagram
  participant User
  participant CLI as simplycubed CLI
  participant Config as .github/simplycubed.yml
  participant Env as engineEnv
  participant Runner as Claude Runner
  User->>CLI: run / preflight with engine: claude
  CLI->>Config: load config
  CLI->>Env: validate selected engine
  Env-->>CLI: skip Azure checks
  CLI->>Runner: construct Claude runner
  Runner-->>User: execute via claude -p

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Generated description — verify against the diff.

🤖 Generated with SimplyCubed Code

[codecov]

Codecov Report

❌ Patch coverage is 85.71429% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
cmd/simplycubed/main.go	85.71%	1 Missing and 1 partial ⚠️

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[charlesgreen]

Verified against the acceptance criterion in #95 rather than the diff alone. On this branch, with a config saying engine: claude and no Azure variables set:

$ simplycubed preflight --repo-dir .
preflight ok: config and engine settings are present

and with the engine left at the default, the requirement is still enforced:

error: AZURE_OPENAI_ENDPOINT is not set. ...

codex.WriteConfig is gated on the same condition, so a Claude run no longer writes a provider config it never reads. The docs are scoped correctly, including the caveat that the hosted path remains Codex-only.

Steps 2 and 4 of #95 are untouched, which is correct: they need a change under .github/workflows/, and the App deliberately holds no workflows permission. Filing that separately.