Update pair code docs for empirical companion_platform_id

[mintlify]

Summary

Aligns the pair code documentation with oxidezap/whatsapp-rust@c6603a5 (oxidezap/whatsapp-rust#595), which:

• Renames the wire enum to CompanionWebClientType and switches its representation from i32 (code()) to single-byte ASCII (wire_byte()).
• Adds AndroidPhone ('e'), AndroidTablet ('d'), AndroidAmbiguous ('f') variants and routes the matching PlatformType values to them.
• Drops the platform_display: String field from PairCodeOptions; the display string is always derived. platform_id is now Option<CompanionWebClientType> (auto-derives when None).
• Emits Android (<OS>) for Android variants in companion_platform_display.

Files updated

• concepts/authentication.mdx — replaced the obsolete PlatformId enum block with CompanionWebClientType (wire bytes), updated PairCodeOptions, added companion_platform_display rules.
• api/bot.mdx — fixed the with_pair_code example (no platform_display, platform_id: Some(CompanionWebClientType::Chrome)).
• api/client.mdx — updated pair_with_code parameter description.
• quickstart.mdx — fixed the customization snippet.