[codex] Fix transit card balance readers

[Lakr233]

What changed

• Updates Octopus balance offsets to follow the public 2017 schedule: 350 before 2017-10-01, 500 afterward.
• Masks the high spare bit in T-Union balance responses and keeps the dual-purse display behavior aligned with Metrodroid.
• Makes KSX6924 AID probing continue after recoverable SELECT status errors.
• Adds TWD balance formatting for EasyCard parsing work and aligns Japan IC balance offset references.
• Expands transit-card research notes with Metrodroid and FareBot references, including EasyCard Classic dump layout.

Validation

• swiftformat --swift-version 6.2 on changed Swift files
• npx --yes prettier --write docs/Transit-Card-Research.md
• git diff --check
• xcodebuild test -scheme CoreExtendedNFC -destination "platform=iOS Simulator,id=EEC22792-5938-4D4B-81EC-610FEA2ED56B"
• xcodebuild -project Example/CENFC.xcodeproj -scheme CENFC -destination "generic/platform=iOS Simulator" build

Notes

Classic EasyCard remains a decrypted-dump parsing target on iOS. The new TWD formatting and documented layout prepare the parser work without adding a live MIFARE Classic authentication path.