docs: add Chinese READMEs for ESP-IDF examples

[Y1hsiaochunnn]

Summary

• Add Chinese README_CN.md copies for all English README files under examples/esp-idf.
• Add bidirectional language links between English and Chinese README files.
• Refine ESP-IDF example docs with practical configuration notes, including ESP32-P4 Platform wording for the Brookesia Phone example.

Checks

• git diff --check -- examples/esp-idf
• Recursive README link check: 24 English README files and 24 Chinese README files, all mutually linked.
• ESP-IDF build not run; changes are documentation-only.