refactor/fix: code quality, filter fixes, expand hints, smoke-v3

[chenliuyun]

Summary

Post-review improvements across three areas: code quality refactoring, two bug fixes, and smoke-v3 test infrastructure.

Refactoring

• Extract exitWithError() helper in output.ts (string or options overload) — eliminates ~17 repeated isJsonMode() ? emitJsonError() : console.error() + process.exit() blocks across batch.ts, mcp.ts, devices.ts
• Replace private isJsonRequested() duplicates in index.ts and config.ts with the shared isJsonMode() import

Bug fixes

• field-aliases.ts: remove 'category' from controlType aliases — prevents collision where --filter category=X could match controlType instead of the physical/IR classification field
• devices.ts: add controlType to LIST_FILTER_CANONICAL, LIST_FILTER_TO_RUNTIME, and the matchesFilter entry shape so --filter controlType=X actually works (was documented but silently ignored)
• mcp.ts: remove dead loadConfig import; replace EOF-only stdin handler with unified graceful shutdown (SIGTERM + SIGINT + stdin end, isShuttingDown guard, 30 s force-exit timeout)

Feature

• devices describe now shows a tip line for device types that support devices expand (Air Conditioner, Curtain, Curtain 3, Blind Tilt, Relay Switch 2PM); --json output includes an optional expandHint: { command, flags, example } field

Tests

• devices.test.ts: --filter controlType=Bot, --filter roomName=Living, read-only device still rejected with --allow-unknown-device
• mcp.test.ts: send_command case normalization (turnon → turnOn)
• mcp-stdio.test.ts: MCP stdio graceful shutdown (stdin EOF, SIGTERM)

smoke-v3 fixes

• analyze.py: remove duplicate if dim == "real.mutate" branch that was double-counting alongside meta.real_mutate
• runner.py: extract check_real_mutate_success(); add --json flag to allowlist mutate commands; validate ok:true in CLI envelope; add meta={real_mutate:True} so the counter in analyze.py fires

Test plan

• npx vitest run — all tests pass (1 pre-existing events.test.ts failure unrelated to these changes)
• npx tsc --noEmit — no type errors
• switchbot devices describe <acId> — shows expand tip at the end
• switchbot devices describe <acId> --json | jq .expandHint — returns { command, flags, example }
• switchbot devices list --filter controlType=Bot — returns matching devices