feat: add reset-to-default controls

[zefutoff]

Summary

• add a global reset-to-default operation
• restore the main dictionary to all variants
• restore every Grammalecte rule option to its upstream default
• clear the personal dictionary
• persist the reset across engine restarts
• add an explicit confirmation dialog before destructive reset
• expose the reset control from correction settings
• mark reset-to-default controls complete in the roadmap

Validation

• real QuickJS / Grammalecte reset regression test
• Android instrumentation verifies persistence across engine restart
• manual validation on Samsung Galaxy S21 / Android 15
• verified rule reset
• verified dictionary reset to all variants
• verified personal dictionary clearing
• make check
• make assemble
• git diff --check
• final APK does not request android.permission.INTERNET