Good First Issue: Add CLI doctor troubleshooting examples

[squaeragent]

Improve the public CLI docs with copy-paste troubleshooting examples for common
zero doctor warnings: missing API token, paper API not running, and live
preflight refusing closed.

Acceptance:

• The docs show exact commands and expected safe output snippets.
• The examples do not imply live trading is ready by default.
• The first-10-minutes path links to the new troubleshooting section.
• just docs-check passes.

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Seeded from docs/launch-issues.md. Keep scope small and paper-safe.

[squaeragent]

Implemented in 12865e2 with docs/cli-doctor-troubleshooting.md. Verified locally with just docs-check, hardening/public-readiness gates, issue drift check, and just paper-api-smoke; remote CI, CodeQL, OpenSSF Scorecard, and Secret Scan are green on 12865e2.