Wake word "Hi, StackChan" not recognized + Request for custom wake word support #94

Problem

The default wake word "Hi, StackChan" does not respond reliably. Tapping the screen works fine, confirming the microphone is functional.

The pronunciation of "StackChan" varies significantly across regions and languages. Japanese speakers naturally say "スタックチャン" which differs from how
the Wakenet model may have been trained.

Observation from source code

Kconfig.projbuild already defines USE_CUSTOM_WAKE_WORD with Multinet support, including configurable threshold. However:

1. This is a compile-time option, not user-configurable at runtime
2. The custom wake word input uses pinyin (Chinese phonetics), which doesn't help non-Chinese users
3. The official documentation states "custom wake word support is not yet available"

Requested improvements

1. Short term: Improve recognition of "Hi, StackChan" for Japanese speakers, or allow sensitivity adjustment (threshold is already in Kconfig as
   CUSTOM_WAKE_WORD_THRESHOLD, default 20%)
2. Long term: Expose custom wake word configuration to users via the StackChan World app, supporting non-Chinese phonetics

Environment

• Device: StackChan (Kickstarter edition)
• Firmware: v1.4.2 (latest)
• Language setting: Japanese
• Microphone test: Passed
• Screen tap wake: Works correctly
• Tested in quiet room, various distances and volumes

Reference

• firmware/main/Kconfig.projbuild line 687-745: Wake word configuration
• Official docs state: "custom wake word support is not yet available"