Correct Core400S CADR and Room Size limits

[EdenNelson]

Correct the Core400S CADR constant and constrain the Core400S Auto Mode Room Size number to the documented model-specific range.

Fixes #37

Summary

• Set Core400S CADR to 442 m³/h.
• Update Core400S Room Size docs from 9-83 m² / 97-894 ft² to 9-38 m² / 97-409 ft².
• Add Core400S efficiency_room_size YAML bounds: min_value: 9 and max_value: 38.
• Update Core400S builder YAML mirrors and the root model table.

Validation

• git diff --check passed.
• Editor diagnostics reported no errors in components/levoit/levoit.cpp.
• Targeted searches confirmed the Core400S corrected values and YAML bounds are present.
• ESPHome 2026.5.0 local Core400S compile passed against this branch.
• Compile warning scan still reports the existing fan preset API deprecation on clean upstream main; that warning is unrelated to this PR and is addressed separately in Fix ESPHome fan preset deprecation warning #36.
• Live stacked-branch validation on a Core400S passed using EdenNelson/levoit@integration/core400s-auto-profile-stack, which contains this change plus Fix ESPHome fan preset deprecation warning #36: ESPHome 2026.5.1 build/OTA succeeded and runtime reported Current CADR as 442 m³/h.

Follow-up

Live testing also showed an existing Core room-size decode round-trip issue: setting 9 m² can echo as 8, and setting 38 m² can echo as 37. That appears to be caused by decoded float room-size values being truncated through the current number publish path. This PR intentionally does not change Core room-size protocol encoding/decoding behavior; that belongs in a separate focused fix.

Disclosure

This PR was prepared with GitHub Copilot/AI assistance and human-in-the-loop review. Live validation was performed by a human on a Core400S using air-purifier-office.yaml.