docs: localize setup guide and clarify adb reverse

[dxcsmam]

What changed?

• Added complete Simplified Chinese and Japanese versions of the manual setup guide.
• Added language navigation to all three setup guides.
• Updated the Chinese and Japanese READMEs so every manual-setup link opens the matching localized guide.
• Clarified that adb reverse may need to be reapplied after a USB reconnect, phone reboot, or ADB server restart.

Why?

The reverse-port mapping belongs to the current ADB device connection. Users could reconnect a phone and find that the Android client no longer reaches the local backend without knowing that the mapping must be recreated.

Closes #39.

Testing

• Verified that all relative documentation links resolve.
• Confirmed that the three guides have matching sections, lists, commands, and configuration blocks.
• Checked that each README links only to its matching guide language.
• Confirmed that client/start.sh runs adb reverse tcp:7777 tcp:7777.
• Ran git diff --check.

Device verification

Not applicable — documentation-only change.

Notes

No runtime code or device behavior was changed.