fix(cli): fail on remaining diagnostics after --fix

[luojiyin1987]

What changed

Keep Core's remainingSummary in BatchLintItem.
Use the remaining error and warning counts to decide the --fix exit code.
Check every file result, including results excluded from writeback.
Fail if a file fix result lacks remaining counts.
Keep stdin output as Markdown only.
Print each file's remaining error and warning counts to stderr.
Print the same summary to stderr for stdin input.

Why

--fix could return exit code 0 while errors or unsuppressed warnings remained.
The previous check only handled rule execution errors.

Verification

• Before this change, four real CLI cases returned 0 when they should return 1.
• npm run lint passed.
• npm test -- --runInBand passed: 27 suites and 238 tests.
• git diff --cached --check passed.
• Tests cover file and stdin input, warning suppression, successful fixes, and rule failures.
• Real CLI tests check the remaining-count message in stderr.

Redactions

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