v0.32.0 — Review diffs from stdin

Added\n\n- triss review --stdin now accepts an explicitly piped diff without Git, GitHub, changed-file, or linked-ticket discovery.\n- Stdin review preserves valid UTF-8 exactly, rejects malformed bytes, TTY input, empty input, and conflicting PR/--base sources before provider or model resolution.\n\n## Security\n\n- CLI and MCP reviews now share the same untrusted-data system prompt and per-request boundary markers for metadata, ticket text, and diffs.\n\n## Verification\n\n- Node.js 22 and 24 test suites passed.\n- pnpm package-consumer smoke test passed.\n- CodeQL passed.\n\nChanges: PR #36\nRelease preparation: PR #38