fix(loop-sync): honor json output flag

[Zhang-986]

Summary

Make loop-sync --json emit the machine-readable drift report it documents, so CI and agent loops can parse the result reliably.

Changes

• New pattern or starter (followed templates/pattern-template.md + updated registry.yaml)
• Doc / example improvement
• Tool change (loop-sync)
• Story (includes real failure or surprise + lesson)

Details

loop-sync already parsed --json, but parseArgs did not return the parsed json flag. As a result, users running loop-sync <target> --json still received the human-readable report.

This fixes the CLI contract by carrying the parsed flag through to main, and adds a CLI-level regression test that parses stdout as JSON even when loop-sync exits with the existing warning code.

Checklist (from CONTRIBUTING)

• All required sections present for patterns
• Links work from README, patterns/README, starters/README, docs/index
• No secrets, tokens, internal company URLs
• STATE.md* examples use .example suffix
• Safety-related content references docs/safety.md
• Ran node tools/loop-audit/dist/cli.js . through scripts/ci-audit-gates.sh

Testing / Dogfood

• cd tools/loop-sync && npm test
• bash scripts/ci-validate-gates.sh
• bash scripts/ci-audit-gates.sh
• git diff --check

Screenshots / Examples (if UI or command output)

Before this change, loop-sync --json emitted the human-readable Loop Sync Report. The added regression test now executes the built CLI with --json and verifies stdout parses as JSON.

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This template enforces the high bar this reference is known for.